I disagree.
Read this site carefully.
http://ancienthistory.about.com/od/peloponnesianwar/qt/073009CausesofPeloponnesianWar.htm
What was the cause of the peloponnesian war?
A. Greeks sought revenge for the persian wars.
B. Sparta wanted control of the powerful athenian army.
C. A spartan murdered the athenian ruler pericles.
D. Many greeks outside of athens resented athenian domination.
I got C.
2 answers
http://en.wikipedia.org/wiki/Pericles#Last_military_operations_and_death