Quiz playing is a wonderful way to increase your knowledge of English as a Second Language. Remember that all of our ESL quizzes have titles that are both friendly and technical at the same time… In the case of this quiz you might like to tell your friends about “Must You?” but no doubt your teachers will talk about the “Obligations quiz”! If you hear a technical term and you want to find a quiz about the subject then just look through the list of quiz titles until you find what you need.
If an English speaker wants someone else to stop doing something (maybe thoughtless, and/or repeated) that is annoying them - like swinging their feet back and forth under a seat, and banging it every time - they may simply ask: 'Must you?' (i.e., 'Do you absolutely have to keep on doing that?').
There are a surprising number of 'shades' of obligation in English: we 'must' balance our finances and we 'must' 'keep calm and carry on', etc..
How strong are you at knowing the best way to phrase these obligations?
'Going to' (Answer 1) suggests that the people in this conversation meant to do it, but forgot or were disorganised, and it is now too late since the deadline has passed.
Answer 2 shifts the perspective onto the company who were running the competition. But the 'expectation' was only general; how could the company have known whether these particular people were thinking of entering, or not?
Answer 4: They were only 'obliged' if they were actually entering; the company couldn't force them to take part!