The correct answer to how Alexander the Great was able to unify the various people he conquered into an empire is b. by adopting the practices of the conquered cultures. Alexander the Great adopted the practices of the various cultures that he conquered. This generated less opposition among the conquered peoples.
Alexander was known for his policy of cultural integration, which included adopting local customs, intermarrying with local populations, and respecting local religions and traditions. This approach helped him to win the loyalty of many of the people in his empire rather than simply imposing Greek culture and practices upon them.