What was the peloponnesian war? how did the war affect the greece?

The Peloponnesian War (431–404 BC) was an ancient Greek war fought by Athens and its empire against the Peloponnesian League led by Sparta. Historians have traditionally divided the war into three phases. it gave the Greek city states more freedom and bigger armies, it also united the Greek Cities. The wars gave Athens control on the league of Greek Cities and a very powerful army.

Ibelieve that the answer is (a).