Assertion : On moon you cannot hear your friend standing at some distance from you.
Reason : There is a vacuum on moon.

Options

A. If both Assertion and Reason are true and the Reason is correct expanation of the Assertion.
B. If both Assertion and Reason are true but the Reason is not correct expanation of the Assertion.
C. If Assertion is true, but the Reason is false.
D. If Assertion is false but the Reason is true.

Explanation

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

### Step 1: Understand the Assertion
The assertion states that "On the moon you cannot hear your friend standing at some distance from you." This is true because sound requires a medium (like air) to travel. On the moon, there is no atmosphere, which means there is no medium for sound waves to propagate.

**Hint:** Consider what is necessary for sound to travel.

### Step 2: Understand the Reason
The reason states that "There is a vacuum on the moon." This is also true. The moon has a very thin atmosphere, which is essentially a vacuum. In a vacuum, there are very few particles, and thus sound cannot travel.

**Hint:** Think about how sound waves propagate and what conditions are necessary for them to do so.

### Step 3: Connect Assertion and Reason
Now, we need to connect the assertion and the reason. The assertion is true because you cannot hear your friend on the moon, and the reason is true because there is a vacuum on the moon. The lack of a medium (due to the vacuum) is what prevents sound from traveling.

**Hint:** Reflect on how the reason explains the assertion.

### Step 4: Conclusion
Since both the assertion and the reason are true, and the reason correctly explains why the assertion is true, we conclude that the correct answer is that both the assertion and reason are true, and the reason is the correct explanation of the assertion.

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