Why was Philip of Macedonia able to easily conquer Greece? Sparta had become weakened by disease.
The city-state was too poor.
There had been too many internal wars.
Macedonia was too strong and strategic.

Correct answer is There had been too many internal wars.

Explanation:

First option is not correct as Sparta, along with other Greek city-states were weakened with a series of conflict that started with Peloponnesian war.

Second option is not correct as there were many city states in Greece, not only one.

Third option is correct as Greek city states had fought each for almost a century, and thus became an easy prey to be conquered.

Fourth option is not correct as although Macedonia was a strong country, it wouldn't be easy to defeat Greeks if they already weren't in problems.

is there multiple choice or do you need like an essay answer?