What was one effect of the Peloponnese war? a. Macedonia invaded Greece.
b. Sparta allied with Macedonia
c. Athens took over Macedonia.
d. Macedonia defeated the Greek navy

An effect of the Peloponnese war was that Macedonia invaded Greece.

Explanation:

The Peloponnese war was a war between Sparta and Athens, with Sparta coming out as a victor in it. The lack of political absence of Athens for some time in the region because of the engagement in the war with Sparta gave opportunity the Macedonians to be able to speed up their progress, implement reforms, and rapidly become a force to be reckoned with.

The Macedonians managed to reform their army and strengthen their economy, and for the Hellenic city-states, this was not a good sign. Phillip II of Macedon attacked the Hellenic city-states and defeated them all, causing a huge loss in military personnel. One city-state that saved itself was Sparta, and there are two reasons for it, one is that they were in good relations with the Macedonians and often allied, and the other because it was of interest to any of the two sides to go in war against each other and suffer losses unnecesarilly.