The answer is:
Adjective clause: "that I recommended"
Words it modifies: "the CD"
Adjective clauses possess a subject and a verb, and present additional information of the words they modify. They are introduced by a relative clause, such as which, that, who, whom and whose. They can also they begin with a relative adverb like when, where and why.
In the sentence given, the adjective clause provides further description of the subject of the sentence, which is the CD.
