The Difference Between a Morpheme and a Phoneme Is That

The difference between a morpheme and a phoneme is that a morpheme is ___ and a phoneme is ___.

A) the system for using words; the system for using grammar
B) the dictionary meaning of a word; how the word sounds
C) practical aspects of language use; the non-verbal communication that occurs with language
D) the smallest unit of meaning in a language; the smallest unit of sound in a language