In the question below, a phrase is given followed by four sentences. Each sentence has one phrase highlighted. The given phrase can be used to replace the highlighted phrase in the sentences. You are required to identify the sentence where the given phrase can replace the highlighted phrase grammatically and contextually. If the given phrase cannot replace any of the highlighted phrase, mark 'none of these' as your answer.  A piece of cake

The phrase a PIECE OF CAKE means something is very easy. This is synonymous to the phrase In option (a), as NOT ROCKET SCIENCE also means an easy task. Here the sentence speaks about the landing of Indian aircraft by an experienced pilot which totally fits contextually and meaningfully with the sentence. Thus A is the right answer. B is incorrect as a BAD HAIR DAY means a day when everything goes wrong. C is incorrect as a BUNCH OF FIVES means getting in a fight. D is incorrect as A BIGGER BANG for our buck means value for money.