why would people of European descent in the late 1600s begin to believe that people of African descent were naturally or biologically inferior to them​

Because of the White Man Burden.

Explanation:

The white mans burden was the beliesf that it was white mans duty to colonize others

the answer is b: the religion they practice.

here's why:

there were many different native american tribes and those with similar characteristics formed a main tribe or nation. each had its own language, religion and customs.

the answer would be:

b. race