Rajesh said, “I bought a car yesterday.”

The correct answer is: Rajesh said that he bought a car yesterday.

The other options are incorrect because they do not accurately reflect what Rajesh said. In option A, Rajesh is saying that you have bought a car, but he is not saying that he has bought a car. In option B, Rajesh is telling us that he had bought a car, but he is not saying that he bought a car. In option C, Rajesh is saying that he bought a car, but he is not saying that he bought a car yesterday.

The correct answer is based on the following rules of grammar:

• When a direct quote is used, the verb tense in the quote should match the tense of the sentence in which the quote is used. In this case, the sentence is in the simple past tense, so the verb tense in the quote should also be in the simple past tense.
• When a direct quote is used, the subject of the quote should be the same as the subject of the sentence in which the quote is used. In this case, the subject of the sentence is Rajesh, so the subject of the quote should also be Rajesh.
• When a direct quote is used, the punctuation should be correct. In this case, the quote should be enclosed in quotation marks and the speaker’s name should be followed by a comma.

Therefore, the correct answer is: Rajesh said that he bought a car yesterday.