I think the bolded words would be "whom Mr. Stein chose". The clause whom Mr. Stein chose is an example of an adjective because the clause describes the word student. Student is the subject of the sentence and is a noun. An adjective describes a noun or another subject. an adverb describes a verb or another adverb.
The answer is D, Music. He was a musician who played the keyboard and sang wonderfully. Sadly he died in 1974.
Answer: (C.) She is the antagonist who creates conflict to move the story forward.
