Answer:
A. by adopting the practices of the conquered cultures
Step-by-step explanation:
Alexander the Great was able to unify the various people he conquered into an empire by "adopting the practices of the conquered cultures".
He conquered Persia, Western India, Egypt and Central Asia and spread Greek ideas in vast areas. In order to unify his large territory, he had respect for the cultures of the people he conquered and spread Greek ideas. He also used religion as a means of unifying the people. He embraced the customs of the people he conquered.