What Effect Did the Discovery of Tobacco as a Cash

What effect did the discovery of tobacco as a cash crop in Virginia have on the colony's labor supply?

A) The British immediately began to import African slaves to do the heavy work on the tobacco plantations.
B) It really had no effect, since tobacco was not thought of as desirable, so Virginians had to turn to other crops, like cotton, to make a living.
C) Early tobacco was a very dangerous product, and quickly killed off the Indians the white settlers had used as slave labor.
D) The British needed more labor, although they initially turned to their "undesirables" as a source.