Answer:
During the period of slave trade, people were brought in from mostly Africa through the Sea.
When they arrived, they were sorted according to their gender, physique and strength. The stronger and physical individuals were selected as prospective farm laborers while the others were assigned to other jobs such as home keeping.
The slaves were then advertised according to their strength and the suitability of job they will be able to perform. The buyers would then come and check the individual out and pay money to the slave masters and take the slaves for their various uses.