What role did warfare in africa play in the slave trade of the late 18th century

Explanation: A) Warfare in Africa reduced the availability of slaves.

B) Many African tribes signed themselves into slavery to escape the warfare.

C) Warfare in Africa increased European desires to "Christianize" African people.

D) Victorious tribes often sold or traded their prisoners to European slave traders.

a.) are both appointed for life

where is the passage

i cant solve it without knowing the passage