I think it's A. By supplying them with raw materials.
The Triangular Trade was an efficient system where the American Colonies, Africa, and the Caribbean all traded manufactures, crops, and slaves with each other.
Note: I could be wrong about the answer. My first guess was D. By providing them with manufactured goods, but was doing a little more research and am now leaning towards A. Just know that I too am unsure of the answer so I may not be the most reliable source.
