In the following which is not the unit of time

Options

A. Leap year
B. Lunar month
C. Light year
D. sidereal year

Answer

To determine which of the given options is not a unit of time, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Identify the Options**: The question provides five options. We will analyze each one to see if it represents a unit of time.

2. **Analyze the First Option - Leap Year**:
- A leap year is a year that has one extra day (February 29) added to keep the calendar year synchronized with the astronomical year.
- **Conclusion**: Leap year is a unit of time.

3. **Analyze the Second Option - Lunar Month**:
- A lunar month is the time it takes for the Moon to complete one full cycle of phases, which is about 29.5 days.
- **Conclusion**: Lunar month is a unit of time.

4. **Analyze the Third Option - Light Year**:
- A light year is defined as the distance that light travels in one year. It is approximately 9.46 trillion kilometers (or about 5.88 trillion miles).
- **Conclusion**: Light year is NOT a unit of time; it is a unit of distance.

5. **Analyze the Fourth Option - Sidereal Year**:
- A sidereal year is the time taken for the Earth to complete one full orbit around the Sun relative to the fixed stars, which is about 365.25 days.
- **Conclusion**: Sidereal year is a unit of time.

6. **Final Conclusion**: Among the options provided, the only one that is not a unit of time is the **Light Year**.

### Final Answer:
The option that is not a unit of time is **Light Year**.