The first answer is correct (A).
It is a social structure practiced until the abolition of slavery in 1863.
The aristocracy was formed by landowners who structure the plantations, as well as entrepreneurs and other powerful. The middle class was made up of ordinary white citizens, like small merchants. The slaves were the basis of this social pyramid, seen only as a capital good, transacted by monetary values.
That was our social structure of the past and it left a patriarchal and racist mentality in the world, unfortunately.