_____ is the only method through which two completely uncharged bodies can be charged.

Options

A. charging by friction
B. charging by conduction
C. charging by conduction
D. none of them

Answer

The correct answer to the question "_____ is the only method through which two completely uncharged bodies can be charged." is **charging by friction**.

### Step-by-Step Solution:

1. **Understanding Charging Methods**:
- There are several methods to charge objects: charging by friction, conduction, and induction. We need to identify which method can charge two completely uncharged bodies.

2. **Charging by Friction**:
- When two uncharged bodies are rubbed against each other, electrons are transferred from one body to the other.
- One body loses electrons and becomes positively charged, while the other body gains electrons and becomes negatively charged.
- This method works solely through the physical contact and rubbing of the two uncharged bodies.

3. **Charging by Conduction**:
- This method involves direct contact between a charged object and a neutral object.
- Since both objects in our question are uncharged, this method cannot be applied.

4. **Charging by Induction**:
- Induction involves charging a neutral object by bringing a charged object close to it without direct contact.
- However, this method requires at least one charged object, which is not applicable in our case where both bodies are uncharged.

5. **Conclusion**:
- After analyzing all the methods, we conclude that **charging by friction** is the only method that allows two completely uncharged bodies to become charged.

### Final Answer:
**Charging by friction** is the only method through which two completely uncharged bodies can be charged.