The best explanation for the causes of the Slave Code of 1740 is:
The Slave Code of 1740 was caused by a large-scale, deadly slave rebellion in South Carolina, and growing fears of future revolts.
This conclusion is drawn from the historical context in which the Slave Code was enacted, particularly in response to the Stono Rebellion of 1739, which instilled significant fear among slave owners and led to more stringent regulations on enslaved people.