Compared to Greece, why was Persia able to organize such a massive empire?

AIts territory was connected by flat plains, unlike Greece's steep mountains and numerous islands.

BIts mastery of sea travel allowed it to govern lands that lay thousands of miles from its capital.

CIts many islands were relatively close together, allowing for easy communication and governance.

DIts population was more culturally unified than Greece's population, which consisted of many different ethnic groups.