He __________ not wear a neck-tie if he doesn't want to.
To indicate absence of compulsion, the blank should best be filled by

The correct answer is Option D (need).

Key Points:
• This question evaluates the candidate's understanding of Modal Auxiliaries, specifically identifying the correct modal to express the 'absence of compulsion' or necessity, a common testing area in MPSC grammar.
• Option 4 is the correct answer according to the official MPSC answer key. The modal 'need not' (or 'needn't') is specifically used in English to indicate that there is no obligation or compulsion to perform an action.
• Let us analyze why the other options are incorrect. Option 1 ('may not') indicates prohibition or denial of permission, not absence of compulsion. Option 2 ('should not') is used to offer negative advice or indicate that something is a bad idea. Option 3 ('dare not') indicates a lack of courage to do something. None of these express the idea that an action is simply unnecessary.
• A common MPSC trap is confusing 'need not' (absence of obligation) with 'must not' (strict prohibition).
• Understanding the exact emotional or authoritative tone (permission, obligation, advice) of each modal verb ensures higher accuracy.
• Key Takeaway: Remember: Use 'need not' to show an absence of obligation or necessity (you don't have to do it). Use 'must not' to show strict prohibition (you are not allowed to do it).