Answer: C) Adjective clause.
Explanation: An adjective is a word or a group of words that modifies a noun or a pronoun, by giving them some attribute. An adjective clause is a dependent clause that acts like an adjective, they start with words such as that, when, where, who, whom, whose, which, and why. In the given sentence, the phrase "whose many wives fared badly" is an adjective clause that modifies the noun "king."
