Please choose the correct option and give reasons also.

Dear Student,

The correct answer is option (b) most of what.

This is because in the given sentence, we need to use the superlative degree and 'most' is the superlative form of many and much. It indicates the greatest in number, quantity etc. There is a comparison here and in such situations, most is used. So option 'a' and 'd' become incorrect.

Regarding option (c), the given sentence is generic and does not talk of anything specific while 'this' is used for something specific. So, option (c) also becomes incorrect.

Regards