Why did Athens and Sparta form an alliance? A. To share military training programs

B. To colonize the Mediterranean coast

C. To resist conquest by the Persians

D. To exchange needed raw materials

C. To resist conquest by the Persians .

Explanation:

Only option C is correct as during the Greco-Persian war these two city-states were practically obliged to form an alliance as Persians attacked them and made a great danger for whole Greece.

Although Sparta and Athens were never in good relations they had to put aside their differences to defeat the common enemy.

All other answers are wrong as they are not historically accurate.

nothing certain is known about what happened, but it seems that the country declined gradually, perhaps due to bad government, or, more likely, due to a series of bad harvests, which resulted in widespread and recurrent famine.