Final answer:
The component of gasoline that contributes the most to its high enthalpy of combustion is octane, an alkane which is part of the liquid alkanes in gasoline.
Step-by-step explanation:
The component of gasoline that gives it such a high enthalpy of combustion is c) Octane. Octane is a part of the liquid mixture of continuous- and branched-chain alkanes that comprise gasoline. Alkanes are known for their highly exothermic combustion reactions with oxygen, producing carbon dioxide and water. This reaction releases a significant amount of energy, which makes substances like octane desirable as a fuel component. Beside octane, gasoline contains various additives to improve its performance, but octane is paramount for the high energy release during combustion. In contrast, methane (a), ethanol (d), and butane (b) are not the primary reasons for gasoline's high enthalpy of combustion, although methane is the principal component of natural gas and butane is used for gasoline blending and as a fuel gas.