Assertion: Light year is the distance that light travels with velocity of `3xx10^(8)ms^(-1)` in one year.
Reason: Light year is the unit for measuring time.

Options

A. if both assertion and reason are true reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation fo assertion.
C. If assertion is true but reaso is false.
D. IF both assertion and reason are false.

Explanation

To solve the question regarding the assertion and reason about the light year, we will analyze both statements step by step.

### Step 1: Understand the Assertion
The assertion states that "Light year is the distance that light travels with a velocity of \(3 \times 10^8 \, \text{m/s}\) in one year."

**Analysis**:
- The speed of light in vacuum is approximately \(3 \times 10^8 \, \text{m/s}\).
- A light year is defined as the distance light travels in one year.

### Step 2: Calculate the Distance Light Travels in One Year
To confirm the assertion, we can calculate the distance light travels in one year.

1. **Convert one year into seconds**:
- 1 year = 365 days
- 1 day = 24 hours
- 1 hour = 3600 seconds

Therefore, the total number of seconds in one year is:
\[ \text{Total seconds} = 365 \, \text{days} \times 24 \, \text{hours/day} \times 3600 \, \text{seconds/hour} \]
\[ = 365 \times 24 \times 3600 = 31,536,000 \, \text{seconds} \]

2. **Calculate the distance**:
Using the formula:
\[ \text{Distance} = \text{Velocity} \times \text{Time} \]
\[ \text{Distance} = (3 \times 10^8 \, \text{m/s}) \times (31,536,000 \, \text{s}) \]
\[ = 9.461 \times 10^{15} \, \text{meters} \]

This confirms that the assertion is correct.

### Step 3: Understand the Reason
The reason states that "Light year is the unit for measuring time."

**Analysis**:
- A light year is not a unit of time; it is a unit of distance. It measures how far light travels in one year, not the duration of time itself.

### Conclusion
- The assertion is true: Light year is indeed the distance that light travels in one year.
- The reason is false: A light year is not a unit of time; it is a unit of distance.

### Final Answer
The correct conclusion is that the assertion is true, but the reason is false.