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.

A. Since banks usually give gifts

B. to customers who deposited large amounts,

C. it is worthwhile that you bargain with them

D. before you choose a particular bank

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