Answer:
Plantation agriculture was labor-intensive, meaning, that it needed many workers.
Besides, it mostly consisted of cash crops like tobacco, rice, sugar cane, and cotton, that have to be cultivated regions that have very warm and humid climates like the Southeastern United States, and the Caribbean.
For these two reasons, plantation owners needed a vast supply of cheap workers, who could endure the difficult conditions of heat, humidity, and tropical diseases like malaria.
The best labor they found were African slaves: they were numerous, they were cheap, and they could resist tropical diseases because most of these diseases were already present in Africa.
