Goodbye! I’ll see you . . . . . . . . the morning. A. in B. on C. at D. None of the above

The correct answer is: in.

The preposition “in” is used to refer to a period of time, such as a day, week, month, or year. In this case, the speaker is saying goodbye and indicating that they will see the listener again in the morning. Therefore, the preposition “in” is the most appropriate choice.

The preposition “on” is used to refer to a specific day or date. In this case, the speaker is not referring to a specific day, so the preposition “on” is not the most appropriate choice.

The preposition “at” is used to refer to a specific time. In this case, the speaker is not referring to a specific time, so the preposition “at” is not the most appropriate choice.

The preposition “none of the above” is not a correct answer to the question.