A prefix such as in the word unhappy, can be called a?

Question

My answer was a morpheme but can't it also be called a phoneme?

Answer 1

un-

Yes, it's a morpheme because it carries one unit of meaning.

However, it's made by combining two phonemes: /u/ and /n/

https://en.wikipedia.org/wiki/Phoneme

Answer 2

a trick question because? of can be called

Answer 3

I don't understand that. Please re-type and proofread before you hit Post.

Answer 4

is this a trick question, because the question contained the word (can)
and un is a morpheme, not can be called