4. Why was slave labor so important to the Southern economy? South Slave labor freed the upper class to work at their white collar jobs. (B) Workers were needed for the many factories. Workers were needed for larg e-scale plantation farming. D) Southerne rs weren't used to working.

Slave labor was crucial to the Southern economy primarily because workers were needed for large-scale plantation farming. The Southern economy relied heavily on agriculture, particularly the cultivation of cash crops like cotton, tobacco, and rice. These crops required extensive labor to plant, maintain, and harvest, and slave labor provided a cost-effective means to meet these labor demands. Therefore, the correct answer is:<br /><br />(C) Workers were needed for large-scale plantation farming.