Which factor was a key reason that Greek city states had strong economies?

stable governments.

Explanation:

The factor that was a key reason that the Greek city-states had strong economies was a stable government. Athens was the main city-state government in ancient Greece

“i think it is very plausible that if there are five votes to end the death penalty, it could be with the people who are on the court right now,” - smith

so basically it is not clearly and consistently imposed