Which of these best explains the reason for african slaves being brought into the british colonies in southern north america in the 17th century?

A)  The economy of Southern colonies needed cheap labor.

Let's eliminate other options. The question asks about African slaves being brought in to Southern North America. Even though the Northern colonies had opinions about bringing in slaves from Africa, it did not effect the Southern colonies' decision. This eliminates options B and D. The Southern colonies needed cheap labor in order to provide agricultural products at an affordable price. Refusing to use Indians as forced labor furthers the need for cheap labor.

well its not not rising unemployment and falling inflation.

hope this good !