The potential energy is inversely proportional to square of distance between the charges.It also depends whether both charges are of same or opposite sign, if both are of same sign then potential energy will decrease and if opposite charges then it will increase.

When the separation between two charges is increased, the electric potential energy of the charges may increase or decrease.

Explanation:

Electric potential energy is the energy possessed by a system of charges due to their positions relative to each other. The formula for electric potential energy is given by:

PE = k * (q1 * q2) / r

where PE is the electric potential energy, k is the electrostatic constant, q1 and q2 are the magnitudes of the charges, and r is the separation between the charges.

Now, let's consider the different scenarios when the separation between two charges is increased:

1. Charges of the same sign (both positive or both negative):
- When the charges are brought closer together (decrease in separation), the electric potential energy decreases. This is because the charges repel each other and work is done to move them closer against the repulsive force.
- When the charges are moved further apart (increase in separation), the electric potential energy increases. This is because the charges are now farther away from each other, reducing the repulsive force between them.

2. Charges of opposite sign (one positive and one negative):
- When the charges are brought closer together (decrease in separation), the electric potential energy decreases. This is because the charges attract each other and work is done to move them closer against the attractive force.
- When the charges are moved further apart (increase in separation), the electric potential energy increases. This is because the charges are now farther away from each other, reducing the attractive force between them.

In summary, the electric potential energy of charges may increase or decrease depending on the nature of the charges (same or opposite sign) and the change in separation between them. Therefore, the correct answer is option 'D' - the electric potential energy may increase or decrease.