-What Is One Reason That Cotton Cultivation Spread Westward Across

-What is one reason that cotton cultivation spread westward across the Black Belt that ran from Alabama to east Texas after 1820?

A) Cotton depleted the soil of nutrients, so growers needed fresh land.
B) Cotton cultivation required much labor, and the western slave trade was thriving.
C) An economic boom was taking place in western cities located on the Black Belt.
D) Canals had reached westward to the new plantations located throughout the Black Belt.