Final answer:
The process of breaking down words into their basic meaning parts, or features, is known as morphology, which deals with morphemes, the smallest meaningful units in a language.
Step-by-step explanation:
Breaking down words into their constituent meaning parts, or features, is called morphology. Phonemes, which are the basic sound units of a language, combine to form morphemes, the smallest units of language that carry meaning. Semantics is the process by which we derive meaning from morphemes and words. Syntax refers to the organization of words into sentences. Thus, the correct answer to the student's question is d) Morphology.