Natural gas is mostly methane by composition

Steps:

• Recall that natural gas is a fossil fuel extracted from underground reservoirs.
• Identify its primary chemical makeup: over 90% hydrocarbons, mainly simple alkanes.
• Focus on the simplest alkane, which dominates the mixture.
• Confirm through standard knowledge: methane is the chief component.

Why C is correct:

• Methane (CH₄) constitutes 70-90% of natural gas, as defined by its geological formation from organic decay.

Why the others are wrong:

• A. Ethane (C₂H₆) is present but only 0-20%, not the main compound.
• B. Ethene (C₂H₄) is an alkene, not a significant part of natural gas's alkane-based composition.
• D. Methanol (CH₃OH) is an alcohol derived from gas processing, not naturally occurring in raw gas.

Final answer: C