What Was the Purpose of the British Policy of Indirect

What was the purpose of the British policy of Indirect Rule?

A) To force Africans to convert to Christianity.
B) To assimilate Africans into European thought and culture in order to "civilize" them.
C) To force African traditional rulers to send their children to school.
D) To make use of traditional African rulers to assist in administering the colonies.
E) None of the options are correct.