The smallest planet in the solar system is:

Options

A. Mercury
B. Venus
C. Earth
D. Mars

Explanation

**Step-by-Step Solution:**

1. **Identify the Question**: The question asks for the smallest planet in the solar system among the options provided: Mercury, Venus, Earth, and Mars.

2. **Recall the Planets**: There are 8 recognized planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

3. **Determine the Size of Each Planet**:
- Mercury
- Venus
- Earth
- Mars
- Jupiter
- Saturn
- Uranus
- Neptune

4. **Compare the Sizes**: Among these planets, we need to compare the sizes of Mercury, Venus, Earth, and Mars specifically.

5. **Identify the Smallest Planet**: Upon comparing their sizes, it is known that Mercury is the smallest planet in the solar system.

6. **Conclusion**: Therefore, the answer to the question is Mercury.

**Final Answer**: The smallest planet in the solar system is Mercury.

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