Read the assertion and reason carefully to mark the correct option out of the options given below: Assertion: Straight chain alkanes have very low octane number. Reason: Quality of gasoline is measured in terms of octane number.

• A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
• B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
• C. If assertion is true but reason is false.
• D. If the assertion and reason both are false.