Answer:
A. The electric energy is due to the protons’ charges and positions within an electric field, so their energy is a form of potential energy.
Explanation:
Proton is subatomic particle with positive charge. Things with charge will pull the opposite charge and repel/push the same charge. The closer their position, the higher the energy will be. It should be potential energy since your location(how close it is) determine how strong the energy.
It's not thermal or kinetic energy since this doesn't involve any movement yet.