Final answer:
B.encomienda. The encomienda system allowed Spanish colonists to demand labor from Native Americans in a certain area for mining and plantations.
Step-by-step explanation:
The Spanish system that allowed colonists to demand labor from Native Americans in a certain area is called the encomienda system. Under this system, Spanish authorities assigned native workers to mine and plantation owners. Although the system was justified as a means of converting natives to Christianity, it often resulted in forced labor and exploitation.