Answer
The capacitance is divided by four.
Work Step by Step
The capacitance of a parallel-plate capacitor is equal to $$C=\frac{\epsilon_o A}{d}$$ If the new area $A'=\frac{1}{2}A$ and the new distance of separation $d'=2d$, the new capacitance $C'$ equals $$C'=\frac{\epsilon_o(\frac{1}{2}A)}{2d}=\frac{\epsilon_o A}{4d}=\frac{1}{4}(\frac{\epsilon_o A}{d})=\frac{1}{4}C$$ Therefore, the capacitance is divided by four.
