Which of the following was used by coal miners?

Options

A. Match sticks
B. Candles
C. Davy's lamp
D. Kerosene lamp

Explanation

To determine which of the following was used by coal miners, we need to analyze the options based on the safety and effectiveness of lighting in coal mines.

### Step-by-Step Solution:

1. **Understand the Environment**: Coal mines are dark and can contain flammable gases, such as methane. Therefore, any lighting source used must be safe and not cause explosions or fires.

2. **Evaluate Matchsticks**: Matchsticks produce an open flame that can easily ignite surrounding materials. In a coal mine, this poses a significant risk of fire and explosion. Thus, matchsticks are not suitable.

3. **Evaluate Candles**: Similar to matchsticks, candles also produce an open flame. The risk of the flame spreading and igniting flammable gases makes candles an unsafe option for coal miners.

4. **Evaluate Kerosene Lamps**: Kerosene lamps also produce an open flame and can be dangerous in the presence of flammable gases. If a kerosene lamp were to break, the kerosene could ignite, creating a hazardous situation. Therefore, kerosene lamps are not appropriate for use in coal mines.

5. **Identify the Safe Option**: The specially designed lamp mentioned in the transcript uses methane gas. This type of lamp is designed to minimize the risk of fire and explosion. It provides a flame that does not extract heat to the outside, making it a safer option for coal miners.

6. **Conclusion**: Based on the analysis, the correct answer is that coal miners used a specially designed lamp that utilizes methane gas.

### Final Answer:
The correct option is the specially designed lamp that uses methane gas.

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