Greece's many hills were important to early Greek city-states because they: A. Forced Greek leaders to form a united government.
B. Stopped the Persian Empire from attacking Greece.
C. Gave Greek farmers a place to graze their animals.
D. Allowed Greece to trade with other countries.

D. allowed Greece to trade with other countries

A. isn't correct because each of Greek city-states were independent meaning that the Greek leaders weren't forced to make a United government

B. isn't correct because the hills have nothing to do with that war with Grace

C. isn't correct because it was hard for the Greek to farm with the Hills

so D. is the correct answer because they were able to trade easily with other countries because of their Hills and city-states

( I hope this helped answering your question! have a wonderful day everyone!)

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where is the subject? hahahaha

a flatwork hope this