An antecedent of a pronoun is a word that refers to the same thing as this pronoun.
here the pronoun is "theirs"
<em>Rivers stopped flowing along the bank's so that they could hear Orpheus, whose music was harmonious than </em><em>theirs.</em>
(all the words in Boldface refer to the same thing).
What does the "theirs" refer to? it refers to their music, and the they is the Rivers (it's a personification of rivers)
The antecedent is the river!
<span>Anne Bradstreet and Phyllis Wheatley are, respectively, the first and third published female writers in America. [ The surprise to those unfamiliar with these writers comes upon discovery that Anne Bradstreet was also the first published poet in the New World, and that Phyllis Wheatley was an African slave. These two women not only overcame the difficulties of producing and publishing quality</span>
The answer is d it is explained in call of the wild
I believe the best choice is C. This is because an ad's primary purpose is to get as many people to view it as possible. :)