Assertion (A): If the masses of two bodies is doubled, the force reduces to 1/4th of the initial force.
Reason (R): The force of attraction between two bodies is directly proportional to the product of their masses.

Options

A. Both A and R are correct and R is the correct explanation of A.
B. Both A and R are correct but R is not the correct explanation of A.
C. A is incorrect and R is correct.
D. Both A and R are incorrect.

Explanation

To solve the question, we need to analyze both the assertion (A) and the reason (R) given in the problem.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states: "If the masses of two bodies are doubled, the force reduces to 1/4th of the initial force."
- According to the law of universal gravitation, the force of attraction (F) between two masses (M1 and M2) is given by the formula:
\[ F = \frac{G \cdot M1 \cdot M2}{D^2} \]
- If both masses are doubled, we have:
\[ M1' = 2M1 \quad \text{and} \quad M2' = 2M2 \]
- Substituting these values into the force equation gives:
\[ F' = \frac{G \cdot (2M1) \cdot (2M2)}{D^2} = \frac{4G \cdot M1 \cdot M2}{D^2} = 4F \]
- This shows that the new force (F') is actually four times the initial force (F), not one-fourth.

2. **Conclusion about Assertion (A)**:
- Therefore, assertion A is **false**.

3. **Understanding the Reason (R)**:
- The reason states: "The force of attraction between two bodies is directly proportional to the product of their masses."
- This statement is consistent with the formula for gravitational force:
\[ F \propto M1 \cdot M2 \]
- Hence, the reason (R) is **true**.

4. **Final Evaluation**:
- Since assertion A is false and reason R is true, we conclude that:
- A is incorrect.
- R is correct.

### Final Answer:
- The correct answer is that assertion A is false, and reason R is true.