She was born . . . . . . . . 1961. A. at B. in C. on D. None of the above

The correct answer is: C. on

The preposition “on” is used to indicate a specific date or day. In this case, the question is asking about the date of the person’s birth, which is a specific day. Therefore, the correct answer is “on.”

The other options are incorrect because they do not indicate a specific date or day. The preposition “at” is used to indicate a specific time or place. The preposition “in” is used to indicate a general period of time or location. The preposition “none of the above” is used to indicate that none of the other options are correct.