In each of these 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.

A. The part of Madras that interested us the most

B. were the beach and the museum

C. which we recommend to all friends

D. who plan to visit that city

Please do not use chat terms. Example: avoid using "grt" instead of "great".