To solve this question, the user needs to understand the tense of the sentence and the concept of verb tense agreement. The sentence is written in the past tense, which means the correct verb form should also be in the past tense. The user must choose the option that correctly agrees with the tense of the sentence.

Now, let's go through each option and explain why it is right or wrong:

A. was rejecting: This option is incorrect because it is in the past continuous tense which means that the action was ongoing in the past, but it does not fit the context of the sentence. It suggests that the person was continuously rejecting the speaker, but the sentence implies that the person had rejected the speaker before.

B. had rejected: This option is correct. The past perfect tense ("had rejected") refers to a past action that was fully completed before another action in the past. In this case, the rejection happened before the speaker's hesitation to ask her out.

C. rejected: This option is in the simple past tense, which is grammatically correct, but it does not fully convey the temporal relationship between the two events. The past perfect tense (had rejected) is more appropriate in this context.

D. has rejected: This option is in the present perfect tense which refers to an action that started in the past and continues to the present. It is not correct to use this tense to describe an action that occurred entirely in the past.

Therefore, the correct answer is:

The Answer is: B. had rejected