13. which statement about the peloponnesian war is true?

a. a victory over the city-state of syracuse gave athens the wealth and resources it needed to defeat sparta.

b. the athenian navy blockaded shipments of grain to sparta and finally forced it to surrender.

c. a plague that decimated athens's population contribute to the city's defeat by sparta.

d. the other greek city-states refused to take sides with either athens or sparta in the war.