Which of the Following Was a Reason That the Swahili

Which of the following was a reason that the Swahili peoples became brokers for trade linking the Arabian Peninsula,the Persian Gulf,and the western coast of India?

A) The monsoon winds made East Africa a logical end point for Indian Ocean trade.
B) Spices and cotton from Central Africa were desired commodities in the Indian Ocean trade.
C) The people of Kilwa were expert ship builders who used the hardwoods of the rain forest to create massive oceangoing canoes propelled by lateen sails.
D) East Africa provided the only source of slaves in the Indian Ocean world.