Answer: City-States
Explanation:
They are considering the end for most city-states because those problems, issues and outside invasions can be very harmful to city-states. Why?
Because they are independent countries that have self-governing. Nowadays, there are only a few city-states. In the past, city-states were, for example, Rome, Athens, Sparta, and those cities can best describe what the city-state is and why issues are harmful for them.
