Look, It . . . . . . . . . A. rains B. is raining C. has been raining D. had been raining

The correct answer is: B. is raining

The sentence “Look, It . . . . . . . . .” is in the present progressive tense. The present progressive tense is used to describe actions that are happening right now. In this case, the speaker is looking at the rain and describing the action of the rain falling.

The other options are incorrect because they do not describe the action of the rain falling as happening right now. Option A, “rains,” is in the simple present tense. The simple present tense is used to describe actions that happen regularly or repeatedly. Option C, “has been raining,” is in the present perfect tense. The present perfect tense is used to describe actions that started in