The Americas started using African slaves, because the Native Americans .

a.

were not good at mining gold and silver

b.

had reached a truce with the British

c.

revolted too much

d.

were dying from disease

B and D seem to be the best answers so that narrows it down

Explanation: The Natives did begin to die from disease but they had also made a truce with the Europeans so the best answer would be B

D.

Explanation:

They had tons of diseases because the colonists had passed them on to the Natives. Since the Natives did not have many diseases because they lived in forests where having a strong immune system wasn't necessary. The colonists did, on the other hand. Disease spread throughout the Native community resulting in millions of deaths.

Short story short, colonists suck.

the answer to your question is:

strong-mayor system