Which of the following is NOT a planet of the sun?

Options

A. Sirius
B. Mercury
C. Saturn
D. Earth

Explanation

To determine which of the following is NOT a planet of the sun, we need to analyze the options provided: Sirius, Mercury, Saturn, and Earth.

### Step-by-Step Solution:

1. **Identify the Options**: The options given are Sirius, Mercury, Saturn, and Earth.

2. **Understand What a Planet Is**: A planet is a celestial body that orbits a star (in our case, the Sun) and has cleared its orbit of other debris.

3. **Classify Each Option**:
- **Mercury**: This is the closest planet to the Sun and is indeed a planet.
- **Saturn**: This is a well-known planet in our solar system, famous for its rings, and it also orbits the Sun.
- **Earth**: This is our home planet and is also a planet that orbits the Sun.
- **Sirius**: This is not a planet; it is a star, specifically one of the brightest stars in the night sky.

4. **Conclusion**: Since Sirius is a star and does not orbit the Sun, it is NOT a planet of the Sun.

5. **Final Answer**: The correct answer is **Sirius**.