What Was the Justification for Slavery Adopted by African Rulers

What was the justification for slavery adopted by African rulers that originated from Islamic societies?

A) They argued that Africans were an inferior race who were better off as slaves.
B) They rationalized it by saying slaves lacked immortal souls.
C) They believed slavery was necessary for economic development.
D) They argued that prisoners of war could be sold and that captured people were chattel.