He said, “Why didn’t you send your application to me ?”

He enquired why I had not sent my application to him.
He enquired why I did not send my application to him.
He enquired why had I not sent my application to him.
He enquired why did I not send my application to him.

The correct answer is: B. He enquired why I did not send my application to him.

The sentence “He said, ‘Why didn’t you send your application to me?'” is in the past tense. This means that the speaker is asking about something that happened in the past. The word “why” is a question word, and it is used to ask for the reason for something. In this case, the speaker is asking why the listener did not send their application to them.

The verb “enquire” means to ask for information. In this case, the speaker is asking for information about why the listener did not send their application to them. The word “did” is the past tense form of the verb “do.” The word “not” is a negative word. The word “send” is a verb that means to deliver something to someone. The word “application” is a noun that means a formal request for something. The word “to” is a preposition that indicates the destination of something. The word “me” is a pronoun that refers to the speaker.

Therefore, the sentence “He said, ‘Why didn’t you send your application to me?'” can be paraphrased as “The speaker asked the listener why they did not send their application to them.”

The other options are incorrect because they do not accurately reflect the meaning of the sentence. Option A is incorrect because it uses the past perfect tense, which is used to talk about something that happened before another event in the past. Option C is incorrect because it uses the past participle “had,” which is used to form the past perfect tense. Option D is incorrect because it uses the present tense, which is used to talk about something that is happening now.