The correct option is B Ninety-five per cent of an individual's life
Option B is the correct answer. Ninety-five per cent of an individual's life is the subject of the sentence. The phrase, in its entirety, is being talked about in the sentence. Option A is only part of what is being talked about. Option C is the object to the preposition by. The phrase given in Option D is the predicate of the sentence since it talks about the subject. Thus, options A,C and D are all incorrect.