Which of the following conclusions about the slave trade is most valid based on the historical record?

Which of the following conclusions about the slave trade is most valid based on the historical record?
O A. It had a negative effect on millions of Africans.
O B. It prevented Brazil from becoming a prosperous country.
O C. It caused Europeans to establish colonies in the Americas.
O D. It caused Africans to unite and support the abolition of slavery.