Answer:
The correct answer is D.
Step-by-step explanation:
Parallel Plate Capacitors are made up of two plates that are connected to each other and there is a set distance between them which is filled with various materials such as air, mika or paper etc. which all affect the capacitance of the capacitor which is it's ability to store electrical charge.
According to the capacitance formula
where C is the capacitance, k is the value of permittivity of the material between the plates, A is the surface area of the plates, E is the constant value of permittivity of free space and d is the distance between the plates, if we double the value of d, the energy stored in the capacitor will be decreased to half of its original value.
I hope this answer helps.