After an 1831 slave rebellion, which state's legislature debated, but did not approve, a plan for gradual emancipation of slaves in that state

The state being referenced in the question is Virginia .

Nat Turner's rebellion was a 1831 slave uprising that resulted in the deaths of 55-65 white citizens. The rebellion was ended in two days and most individuals who were part of this rebellion were found guilty in court or killed. After this rebellion, however, the Virginia legislature considered gradual emancipation. Some individuals felt that this would stop future slave rebellions from happening.

The answer is c. hope that