Answer:
Adjective clause: B. Whose branches had died
Word Modified: C. Tree
Explanation:
An adjective clause is a dependent clause, meaning that it is a group of words that have at least a subject and a verb, but that can not stand on its own because it does not express a complete thought. The function of this clause is to modify nouns.
We can normally identify them because they tend to begin with a relative pronoun (who, whom, whose, that, or which) or a relative adverb (when, where, or why), and they often answer the questions How many? What kind? or Which one?
So, Whose branches had died is the adjective clause because it is dependent, it begins with a relative pronoun that is also the subject: whose, it has a verb: had died, and it modifies the noun The tree. Furthermore, it also answers to the Which one? question: Which three had to be cut down? Answer: The one whose branches had died.
