Explanation:
When two charges are separated by a distance, they exert a force on each other due to their electric fields. This force is given by Coulomb's law:

F = k * (q1 * q2) / r^2

where F is the force, k is the electrostatic constant, q1 and q2 are the charges, and r is the separation between the charges.

The electric potential energy (PE) of the charges is defined as the work done to bring the charges from infinity to their given positions. It is given by the equation:

PE = k * (q1 * q2) / r

Explanation of options:
a) Decreases: This is incorrect because as the separation between the charges increases, the force between them decreases, but the electric potential energy does not necessarily decrease.

b) May increase or decrease: This is the correct answer because the electric potential energy depends on both the magnitude of the charges and the separation between them. If the separation increases while keeping the charges constant, the potential energy will decrease. However, if the charges are increased proportionally to the separation, the potential energy will remain the same. Therefore, it may increase or decrease depending on the specific values of the charges and the separation.

c) Remains the same: This is incorrect because the potential energy can change depending on the specific values of the charges and the separation.

d) Increases: This is incorrect because the potential energy can either increase or decrease depending on the specific values of the charges and the separation.

Conclusion:
When the separation between two charges is increased, the electric potential energy of the charges may increase or decrease depending on the specific values of the charges and the separation. The potential energy is directly proportional to the charges and inversely proportional to the separation. Therefore, changing the separation alone does not determine the change in potential energy.