Petroleum's main components are hydrocarbons Steps:

• Petroleum (crude oil) consists primarily of hydrocarbons, compounds of carbon and hydrogen only.
• Examine each formula: A (CH₃OH) includes oxygen; B (CH₃COH, acetaldehyde) includes oxygen; C (C₂H₆) is carbon and hydrogen only; D (C₂H₅OH) includes oxygen.
• Identify the hydrocarbon: C₂H₆ fits as an alkane.
• Confirm: Alkanes like ethane are key petroleum fractions.

Why C is correct:

• C₂H₆ (ethane) is an alkane hydrocarbon, a major constituent of natural gas and lighter petroleum fractions.

Why the others are wrong:

• A: CH₃OH (methanol) is an alcohol with oxygen, not found in crude oil.
• B: CH₃COH (acetaldehyde) is an aldehyde with oxygen, absent from petroleum.
• D: C₂H₅OH (ethanol) is an alcohol with oxygen, not a petroleum component.

Final answer: C