Final answer:
Gasoline vapors can start a fire slowly initially and then progress rapidly as vapor production increases. Its high volatility and flammability due to its mixture of alkanes make it prone to rapid fire development upon ignition.
Step-by-step explanation:
The student's question regarding the ignition characteristics of various fuel vapors requires an understanding of the chemical and physical properties of these fuels. The correct answer to the student's question is A: Gasoline. Gasoline is a liquid fuel made up of a complex mixture of alkanes, which includes continuous- and branched-chain alkanes containing from five to nine carbon atoms, as well as various additives. As the vapor of gasoline mixes with air and reaches an appropriate concentration, it can be ignited to start a fire. Initially, this process may be slow as the proper air-fuel mixture is achieved, but once started, the fire can progress rapidly as vapor production intensifies due to the high volatility and flammability of gasoline.
In contrast, heavier fuels such as diesel oil and fuel oil, which are primarily mixtures of alkanes with higher molecular masses, have lower volatility and thus their vapors develop fires more slowly. Methanol and natural gas (the primary component of which is methane) also differ in their combustion characteristics compared to gasoline.