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 response accurately reflects the historical context, as the Slave Code was enacted in the wake of the Stono Rebellion of 1739, which heightened fears among white colonists regarding the possibility of further insurrections and led to more stringent control over enslaved populations.