to vs in, of

Basically there are three parts to a typical presentation: the beginning, the middle and the end (or introduction, body and conclusion).
I am not sure why “to” is used here. How about “in” or “of”? Are they good, too?

“to” sounds best to me. “in” is tolerable, but “of” doesn’t seem right. I don’t have a good explanation. After all, one could say “the three parts of a typical presentation are…”. The construction “there are three parts…” seems to alter things.

Thanks Dozy.
I don’t know why but my mind force me to think that “in” and “of” are good and “to” is wrong despite the fact that I know it is wrong.
I would like to hear more opinions/helps about this.

‘To’ is the best option… the parts belong to the presentation.

Is “to” here a short form of “belong to”?

Although the parts do obviously belong to the whole, “to” is not literally short for “belong to”, and in fact “there are three parts belong to a typical presentation” is ungrammatical. If anything it would have to be “belonging to”, but there’s no reason to say that when “to” works fine by itself.