Which statement about the Peloponnesian War is true? A. The Athenian navy blockaded shipments of grain to Sparta and finally forced it to surrender. B. A victory over the city-state of Syracuse gave Athens the wealth and resources it needed to defeat Sparta. C. The other Greek city-states refused to take sides with either Athens or Sparta in the war. D. A plague that decimated Athens's population helped contribute to the city's defeat by Sparta.