Sentence Improvement - Verbal and Reasoning

Directions to SolveIn questions given below, a part of the sentence isitalicised and underlined. Below are given alternatives to the italicised part which may improve the sentence. Choose the correct alternative. In case no improvement is needed, option 'D' is the answer.
Q1:

I took the cycle which he bought yesterday.

A that he bought yesterday

B that which he had bought yesterday

C that he had bought yesterday

D No improvement

ANS:C - that he had bought yesterday

No answer description is available.