When the separation between two charges is increase the electric potential energy of the charges.

Options

A. increases
B. decreases
C. remains the same.
D. may increase or decrease

Explanation

To solve the question about how the electric potential energy of two charges changes when the separation between them is increased, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electric Potential Energy**:
The electric potential energy (U) between two point charges \( Q_1 \) and \( Q_2 \) separated by a distance \( R \) is given by the formula:
\[ U = k \frac{Q_1 Q_2}{R} \]
where \( k \) is Coulomb's constant.

2. **Analyzing the Relationship**:
From the formula, we can see that:
- The potential energy \( U \) is directly proportional to the product of the charges \( Q_1 \) and \( Q_2 \).
- The potential energy \( U \) is inversely proportional to the distance \( R \).

3. **Effect of Increasing Separation**:
When the separation \( R \) between the charges increases:
- Since \( U \) is inversely proportional to \( R \), increasing \( R \) will cause \( U \) to decrease, assuming \( Q_1 \) and \( Q_2 \) remain constant.

4. **Considering the Nature of Charges**:
- If both charges have the same sign (both positive or both negative), the potential energy decreases as the charges move further apart.
- If the charges have opposite signs (one positive and one negative), the potential energy is negative. Increasing the distance will make this potential energy less negative, which can be interpreted as an increase in potential energy.

5. **Conclusion**:
- Therefore, when the separation between two charges is increased, the electric potential energy:
- **Decreases** if both charges are of the same sign.
- **Increases** (becomes less negative) if the charges are of opposite signs.

### Final Answer:
The correct option is D: it may increase or decrease depending on the nature of the charges.