The correct answer to this open question is the following.
The factors that contributed to the growth of the Carolinas were the weather conditions to grow cash crops and the use of slaves.
Cotton was the king of crops in the south. Big plantations produced so much cotton due to the use of slaves. So for the southern economies, slavery was necessary. The weather and the fertile land allowed to grow other crops such as rice, indigo dye, and tobacco that not only were consumed in the Americas but exported to Europe.