The lowest temperature at which a substance catches fire is called its :

Options

A. boiling point
B. melting point
C. ignition temperature
D. critical temperature

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the lowest temperature at which a substance catches fire. This is a specific term used in chemistry.

2. **Identifying Key Terms**: In chemistry, there are several important temperature points related to substances:
- **Boiling Point**: The temperature at which a liquid turns into vapor.
- **Melting Point**: The temperature at which a solid turns into a liquid.
- **Ignition Temperature**: The temperature at which a substance catches fire and begins to combust.
- **Critical Temperature**: The highest temperature at which a substance can exist as a liquid.

3. **Analyzing the Options**: Among the terms identified, we need to focus on the one that specifically refers to the temperature at which a substance ignites.

4. **Selecting the Correct Answer**: The term that describes the lowest temperature at which a substance catches fire is the **Ignition Temperature**.

5. **Conclusion**: Therefore, the answer to the question is that the lowest temperature at which a substance catches fire is called its **Ignition Temperature**.

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