Which provides the strongest evidence that eighteenth-century slavery

Which provides the strongest evidence that eighteenth-century slavery was based on racist views?

a. The status of a person as a slave depended entirely on the amount of money a person had, and blacks had little money.
b. The status of a person as a slave depended on where the person was born, and being born in
Africa made a person a slave.
c. The status of a person as a slave depended entirely on skin color.
d. The status of a person as a slave depended partly on skin color and partly on intelligence.
e. The status of a person as a slave depended entirely on social class.

ANSWER
C