Plantation owners in America often argues that enslaves Africans were better off because they did not have the mental capacity to run their own lives. today, this seems both racist and idiotic. how could such racist beliefs flourish?
a. such beliefs justify social arrangements between dominant and minority groups that benefit those who accept them
b. people knew much less about world history then, so it seemed more plausible
c. people are, by nature, hostile and look to blame their problems on others
d. nineteenth-century science was not well developed, so no authority figures could debunk racist beliefs

There is usually an argument by Americans that owns plantation, that there is no mental capacity for enslaves Africans that they can used in running their life, In today worlds we can consider this racist and idiotic. But this can flourish because as at D: nineteenth-century science was not well developed, so no authority figures could debunk racist beliefs.

As at 19th century, science is still at the earlier stage, it has not developed, and this make the belief to flourish.

Because if science has evolved, the intellectual as well as practical activity which encompass systematic study of the structure as well as behaviour of the physical world of the Africans would have justified them that Afican can run their own life.

Therefore, option D is correct.

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