(A) : Space rockets are usually launched in the equatorial line from west to east. (R) : The acceleration due to gravity is minimum at the equator.

Options

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

Answer

To solve the question, we need to analyze the assertion and the reason provided:

**Assertion (A)**: Space rockets are usually launched in the equatorial line from west to east.
**Reason (R)**: The acceleration due to gravity is minimum at the equator.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- Space rockets are launched from the equator primarily to take advantage of the Earth's rotational speed. The Earth rotates from west to east, and launching rockets in the same direction helps them gain additional velocity, making it easier to reach orbit.

**Hint**: Consider the Earth's rotation and how it affects the launch trajectory.

2. **Understanding the Reason**:
- The acceleration due to gravity (g) is affected by the radius of the Earth. At the equator, the Earth is not a perfect sphere; it is slightly bulged due to its rotation. This means that the radius at the equator is greater than at the poles.
- The formula for acceleration due to gravity is given by:
\[ g = \frac{G M}{r^2} \]
where \( G \) is the gravitational constant, \( M \) is the mass of the Earth, and \( r \) is the radius from the center of the Earth to the point where gravity is being measured.
- Since \( g \) is inversely proportional to the square of the radius, a larger radius (as at the equator) results in a smaller value of \( g \).

**Hint**: Recall the relationship between radius and gravitational acceleration.

3. **Connecting the Assertion and Reason**:
- The assertion is true because launching rockets from the equator allows them to utilize the Earth's rotational speed effectively.
- The reason is also true because the acceleration due to gravity is indeed minimum at the equator due to the larger radius.

4. **Conclusion**:
- Therefore, both the assertion and the reason are true, and the reason correctly explains why rockets are launched from the equator.

### Final Answer:
Both assertion and reason are true, and the reason is a correct explanation of the assertion.