The correct answer is B) it was the best way to grow large cash crops.
A plantation economy helped planters in the South become wealthy in that it was the best way to grow large cash crops.
Southern states heavily supported slavery because they depended on slaves to produce cash crops in large plantations. These crops were used for internal consumption but mostly were traded and exported to Europe. The soil of the southern states was fertile, that is why growing crops was a great business for landlords who used slaves. However, the issue of slavery divided the US citizens. The northerners supported abolition while southerners supported slavery.