"Making":
This option is in the present participle form, which doesn't fit in the sentence structure. The sentence requires a finite verb form.
"Had made":
This option is in the past perfect tense, indicating an action completed in the past before another past event. Since the sentence does not provide any specific past reference, the past perfect tense is not suitable here.
"Make":
This option is in the base form of the verb, also known as the present simple tense. While grammatically correct, it doesn't convey the sense of future action implied in the sentence.
"Made":
This option is in the past simple tense, indicating an action completed in the past. It is not appropriate in this context since the sentence expresses a future action.
"Will make":
This option is in the future simple tense, indicating an action that will occur later. It is the correct choice for this sentence, aligning with the intended meaning of making an appointment in the future.
