When an ant stings a person, it injects a liquid into the skin of the person which contains:

Options

A. acetic acid
B. calcium hydroxide
C. formic acid
D. potassium hydroxide

Answer

To solve the question regarding what liquid an ant injects when it stings a person, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Question**: The question asks about the liquid that an ant injects into a person's skin when it stings.

2. **Identify the Options**: The options provided are:
- 1. Ashtec acid
- 2. Calcium hydroxide
- 3. Formic acid
- 4. Potassium hydroxide

3. **Recall Ant Sting Composition**: It is known that when an ant stings, it injects a substance that can cause pain and irritation. This substance is typically an acid.

4. **Analyze Each Option**:
- **Ashtec acid**: This is not a commonly known acid related to ant stings.
- **Calcium hydroxide**: This is a base and is not related to the composition of ant venom.
- **Formic acid**: This is a known acid that is specifically associated with ant venom. It is also referred to as methanoic acid and is responsible for the pain caused by ant stings.
- **Potassium hydroxide**: This is another base and does not relate to ant stings.

5. **Select the Correct Answer**: Based on the analysis, the correct answer is **Formic acid** (option 3).

6. **Conclusion**: Therefore, when an ant stings a person, it injects a liquid that contains **Formic acid**.

### Final Answer:
The liquid that an ant injects when it stings a person contains **Formic acid**.

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