Which One's Right? - Mixed Detailed 'Proofreading'

The Answer is 1055 (Answer 3) because the clue is the Roman Number system, of which you sometimes see examples in public places, such as the dates of buildings and the numbers of our kings and queens (Henry VIII, for instance).
CLIVe = 154 ( = C + L + '1-before-V')
DIX = 500 + '1-before-10'

Answers 1-3 are examples of Scots family names ('Mc...' or 'Mac...' = 'son of ... / descended from ...'), so these are people whose ancestors were called Donald, etc.
'Machinery' on the other hand, is a collection of machines! (Or it can also be used metaphorically, e.g. 'the political machinery of a nation'.) In a typical British telephone directory, you may notice a whole section of 'M[a]c ...' names. Shortly after that you may find the Irish equivalent, with names like O'Connell, O'Reilly etc. (where 'O'' means 'of ...' ~ almost like 'o'clock'!), and a little further on again, lots of names beginning with P, such as Probert, Pugh and Parry, which are Welsh ('ap' in Welsh, also meaning 'of': so these people are descended from Robert, Hugh and Harold/Henry).
Generally it is a good idea to observe and remember family names when you are learning another language. In many cultures, the names come from:
(1) jobs that people did (Butcher, Baker, Farmer etc.);
(2) places where they lived (Woods, Field, Bridge, Lake, Rivers, Hill, Bywater etc.)
(3) what they were like as people, physically or by character, e.g. Smart, Armstrong, Whitehead;
(4) 'Patronymics' such as Robinson, McTavish, O'Connor and Price ( = 'Ap Rhys').
It can't do much harm if you write down, remember and perhaps investigate some of these. This will give you a bit more cultural insight into our history and the whole matter of how things get their names. What could be more important than the names of a nation's people? And how about your own name? Is there an English equivalent?
If you happen to be Russian and your name is Ivan Petrovich Melnikov, you would be John Peterson Miller, for instance. Well worth some of your thinking-time!

Each of these words sounds like the name of a musical instrument, but only 'flute' is correctly spelt. (It does have another meaning, but you are very unlikely to meet or need that.)
'Symbol' ( = a drawn or written sign, or something representing another idea ~ such as a star to identify good work, or a leading actor) sounds the same as 'cymbal', usually one of a pair of plate-shaped metal instruments that are clashed together during loud music with a band or orchestra. Drum-kits in a pop or folk group will usually include at least one 'open' cymbal (i.e. it can simply be hit with a drumstick), and a pair that are controlled with a pedal so that they sound more gently ~ as in a typical jazz group.
'Base' ( = the bottom of something, like a table lamp) sounds the same as 'bass', which in music usually means the lowest line in the sound. It could be a bass voice (like the deepest male singers), or a bass guitar (which 'drives' the bottom line of most rock music), or a double-bass (like a giant violin, played in an orchestra or dance-band).
'Tuber' is the swollen part of the root system of a plant, where it stores its energy in the form of starch. If that sounds rather technical, remember that the commonest example is probably the potato, which must almost certainly be the most-eaten vegetable in Britain. This word sounds pretty well identical with 'tuba', which is the equivalent of the double-bass in the brass section of an orchestra (or, of course, in a brass band). It is a big, slightly comical instrument made of metal tubing, and it's played by someone blowing quite hard into it and making a rather rude noise with their lips. If you have ever seen a brass band playing a waltz ('Oom-pah-pah ...') or a march or quickstep ('Oom-pah, oom-pah ...'), it's probably the Tuba that was playing the 'Oom' on the strong beats of the music.

'Calling' only has one double letter in it; each of the others has THREE (check them!).
Many languages contain occasional 'accidents' ~ or at least, curiosities ~ of spelling. In French, 'The world was created' = 'la terre a EtE crEEe' (where 'E' stands for 'e with an acute accent', which our system can't display: but there are four of these within a phrase of fewer than 10 letters). You may be interested to note and collect such things in English, along with 'tongue-twisters' ~ phrases and sentences that are hard to pronounce (for English speakers, or anybody) because of the sequence of sounds and how our mouths need to wriggle quickly to say them ...
e.g. 'Can you imagine an imaginary menagerie manager, imagining managing an imaginary menagerie?'
If you like picking up these strange bits of language, it can be fun (as well as frustrating, sometimes) and make the whole learning process more interesting.

Well, they each begin with P... ~ and they're all grammatical words.
Answers 1-3 are all to do with Verbs: Perfect and Present are two of the major tenses, as you're surely aware; a Participle can be either present ([verb]-ING) or past ([verb]-ED).
While we were choosing p-words to do with verbs, there were plenty of others, e.g. Passive (where the verb is 'done to' someone: 'The toast was burned') and Progressive (forms or tenses that involve continuous action, and usually a main-verb form that ends in -ING). We might also have chosen Pronoun, since the Subject of a verb is often in the form of a pronoun ('he said, she went, we had').
A Preposition does not necessarily have much in common with a verb. Usually it is a word like 'under', 'against' or 'during'. But there are a lot of Phrasal Verbs which combine a verb and a preposition to create a particular meaning ('sit up, write down, deal with ... , run off' etc.)

The aircraft itself is obviously the smallest of these things, and an airport is the biggest.
An airstrip is simply a long thin area where a plane can land and take off, perhaps in otherwise quite wild or difficult territory (e.g. in a jungle); but an airfield (Answer 4) consists not only of the runway, but also some other areas, e.g. where planes can be stored and serviced.
To put it another way, an airstrip is almost just a thin straight line ~ that's how it would look on a pilot's map ~ while an airfield would be a two-dimensional shape, like a square or triangle. So the airfield is bigger than just an airstrip.

Answers 1-3 represent the colours of the wires inside a British electric plug: the striped wire goes to the Earth terminal (the bigger one, at the top of the triangle); the other two go to the alternating-current terminals ('Live and Neutral'). There is no red or pink wire in this system.

The other three are related to the verb 'drive': 'he (for instance) drives' (Answer 1), 'they have driven' (Answer 2), 'she is a safe driver' (Answer 4).
'Drivel' is one of many English words for 'rubbish', in the sense of 'meaningless language' ('If you read all the small print in this document, you'll find most of it is legal drivel'). So far as we know, there is no connection with the 'drive' verb here.
We could have offered 'drived' as a non-existent Wrong Answer; the correct past form, of course, is 'drove' ('drive, drove, driven': it's one of those irregular verbs like 'write, wrote, written').

Heathrow is (more or less, once again!) westwards out of Central London.

If you list them alphabetically, they go : Friday, Monday, Saturday, Sunday, Thursday, Tuesday, Wednesday ... so Sunday comes in the middle.