What Was Alexander the Great's Most Successful Strategy for Ruling

What was Alexander the Great's most successful strategy for ruling the lands he conquered?

A) He continued wars of conquest in order to unite people in a common cause.
B) He replaced practically all Persian officials with Greeks and Macedonians.
C) He established free public education in order to make an educated city-state.
D) He reduced the size of the army.
E) He created a synthesis between Greeks and Persians.