Assertion (A): The basic difference between magnetic lines of force and electric lines of force is electric lines of force are discontinuous and magnetic lines of force are continuous.
Reason (R ): Magnetic lines of force exist in a magnet but no electric lines of force exists in a charged body.

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and Rare true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is true

Explanation

To analyze the given assertion and reason, let's break down the concepts step by step.

### Step-by-Step Solution:

1. **Understanding Electric Lines of Force**:
- Electric lines of force represent the direction of the electric field created by electric charges. They originate from positive charges and terminate at negative charges.
- In the case of an electric dipole (which consists of a positive charge and a negative charge), the electric field lines are drawn from the positive charge to the negative charge. This indicates that electric field lines are not continuous; they start at one charge and end at another.

2. **Understanding Magnetic Lines of Force**:
- Magnetic lines of force represent the magnetic field created by magnets. They form closed loops, meaning they do not have a starting or ending point.
- For a magnetic dipole (like a bar magnet), the magnetic field lines emerge from the north pole and enter the south pole, forming continuous loops. This indicates that magnetic lines of force are continuous.

3. **Assertion Evaluation**:
- The assertion states that the basic difference between magnetic lines of force and electric lines of force is that electric lines of force are discontinuous while magnetic lines of force are continuous.
- Based on our understanding, this statement is true. Electric lines of force are indeed discontinuous, while magnetic lines of force are continuous.

4. **Reason Evaluation**:
- The reason states that magnetic lines of force exist in a magnet, but no electric lines of force exist in a charged body.
- This statement is partially misleading. Electric lines of force do exist around charged bodies. For example, a charged body creates an electric field around it, represented by electric lines of force. Therefore, while magnetic lines of force exist in magnets, electric lines of force also exist around charged bodies.

5. **Conclusion**:
- The assertion is true, but the reason is not entirely accurate. Hence, while the assertion is correct, the reason does not correctly support it.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is false.
- Therefore, the correct conclusion is that the assertion is true, but the reason is not a valid explanation for the assertion.