Which was the most important effect of the Peloponnesian War?

Other nations were intimidated by the Greeks.
Other nations saw Greece's lack of unification as weak.
Athens and Sparta were able to prosper as separate city-states.
Athens continued its golden age while Sparta declined and weakened.

The most important effect of the Peloponnesian War was that other nations saw Greece's lack of unification as weak. The war revealed the internal divisions and rivalries between the Greek city-states, particularly Athens and Sparta, which made them vulnerable to outside threats. This perception of Greece's disunity and weakness had a significant impact on how other nations viewed and interacted with Greece.

The most important effect of the Peloponnesian War was that Athens continued its golden age while Sparta declined and weakened.