How did cash crops fuel America's economy?

With cash crops of tobacco, cotton and sugar cane, America's southern states became the economic engine of the burgeoning nation.

Explanation:

By the start of the war, the South was producing 75 percent of the world's cotton and creating more millionaires per capita in the Mississippi River valley than anywhere in the nation

how do you know that

explanation:

answer; i believe the correct answer is (a) the correlation between the cause variable and outcome variable is zero;