In the following questions, a sentence has been divided into four parts and marked a, b, c and d. One of these parts contains a mistake in grammar Idiom or syntax. Identify that part and mark it as the answer.

has indicated his unwillingness In referring to anybody, everybody, everyone, anyone, each etc., the pronoun of the masculine or the feminine gender is used according to the context but when the sex is not determined, we use the pronoun of the masculine gender, as there is no singular pronoun of the third person to represent both male and female, as, Each must do his best.