The best way to extinguish a fire is to cut off the supply of the _____.

Options

A. Non-combustible substance
B. combustible substance
C. Carbon dioxide
D. Sulphuric acid

Answer

To solve the question, "The best way to extinguish a fire is to cut off the supply of the _____," we need to analyze the options provided and understand the concepts of combustion.

### Step-by-Step Solution:

1. **Understanding Combustion**:
- Combustion is a chemical reaction that occurs when a substance (usually a fuel) reacts with oxygen, producing heat and light.

2. **Identifying the Options**:
- The question implies that we need to identify what should be cut off to extinguish a fire. The options provided are:
- Non-combustible substance
- Combustible substance
- Carbon dioxide
- Sulfuric acid

3. **Evaluating Each Option**:
- **Non-combustible substance**:
- These substances do not burn in the presence of air. Cutting off non-combustible substances will not help extinguish a fire, as they do not contribute to combustion.
- **Conclusion**: This option is incorrect.

- **Combustible substance**:
- These are substances that burn in the presence of air and produce heat and light. To extinguish a fire, cutting off the supply of combustible substances (like wood, gasoline, etc.) is essential because without fuel, the fire cannot sustain itself.
- **Conclusion**: This option is correct.

- **Carbon dioxide**:
- Carbon dioxide (CO2) is a gas that can be used to extinguish fires by displacing oxygen. However, it does not need to be cut off as it is not a fuel; instead, it is used as a fire extinguishing agent.
- **Conclusion**: This option is incorrect.

- **Sulfuric acid**:
- Sulfuric acid (H2SO4) does not play a direct role in extinguishing fires. It is not a combustible substance and is not typically used in fire extinguishing methods.
- **Conclusion**: This option is incorrect.

4. **Final Answer**:
- The best way to extinguish a fire is to cut off the supply of the **combustible substance**.