English Grammar: Must I Do the Dishes Now? - Understanding 'Needn't'

The correct answer is B. needn't.

Understanding 'Mustn't' and 'Needn't'

• Mustn't indicates a prohibition or strong obligation not to do something. For example, 'You mustn't smoke in here.'
• Needn't indicates that something is not necessary. For example, 'You needn't do the dishes now.'

In this case, the speaker is saying that it is not necessary to do the dishes immediately. Therefore, 'needn't' is the most appropriate answer.

Other Options:

• May not implies permission or possibility. It doesn't convey the same sense of necessity as 'needn't'.
• Can't means that something is impossible. While it could be used in some situations (if someone is physically unable to do the dishes), it doesn't fit the context of the question.