Which of the following is known as Marsh gas?

Options

A. Butane
B. Propane
C. Ethylene
D. Methane

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the substance that is commonly referred to as "Marsh gas."

2. **Identifying Marsh Gas**: Marsh gas is primarily composed of methane. It is produced in marshy areas due to the anaerobic decomposition of organic matter.

3. **Composition of Marsh Gas**: The main components of marsh gas are:
- Methane (CH₄)
- Hydrogen sulfide (H₂S)
- Carbon dioxide (CO₂)

4. **Analyzing the Options**: The question likely provides several options. We need to identify which one corresponds to the main component of marsh gas.
- Common options might include butane, propane, ethylene, and methane.

5. **Selecting the Correct Answer**: Since methane is the primary component of marsh gas, we can conclude that the correct answer is methane.

6. **Final Answer**: Therefore, the substance known as Marsh gas is **methane** (CH₄).

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