Economics is one of the subject which I have found very difficult since school.

Options

A. Economics is
B. which I have found
C. very difficult since school
D. one of the subject

Answer

D

Explanation

According to the "Subject-Verb Agreement rule", "One of /Each of/None of + Plural Subject + Singular Verb" is grammatically the correct structure for the given sentence. Hence, .One of the subjects(Plural subject). will be answer.