QUESTION
- AAAA
- ABBA
- BAAB
- BBBB
'The time is ripe' is a proverb meaning that 'it is the most favourable time to do something'; 'rife' makes no sense in this context.
'Nook and cranny' is an idiomatic phrase meaning 'every part of a place'; the word 'corner', though it may seem semantically appropriate, cannot be used instead of 'cranny' in this phrase.
'Ill at ease' means 'uneasy' or 'anxious'; 'hard at ease' is meaningless.
To 'drag one's feet' means to 'act slowly or reluctantly'; 'head' cannot be substituted instead of 'feet' in this idiomatic phrase.
Therefore, the correct sequence is BAAB.
Hence, [3].