Question

Why did independent city-states develop in ancient Greece? Choose all answers that are correct. A. Some of the city-states were isolated because they were islands. B. Independent city-states provided protection against attack from other countries. C. The mountains separated groups of people from one another. D. People depended on the many navigable rivers for travel and communication.

Answer 1

Independet city-states mostly developed because either:

a - some of the city-states were isolated because they were islands
This is a good reason why a city-state can develop - as it's physically siolated

c - the mountains separated groups of people from one another.

d - people also depended on navigable rivers for travel and communication
The last one perhaps applying a bit less.