Which fuel types are mentioned in the provided information?

The mention of fuel types in the context of emissions inspection typically focuses on those that are relevant to vehicle emissions and the types of fuels used in the automotive industry. Gas and ethanol are often discussed together because ethanol is a common additive to gasoline, particularly in the form of E85, which is a blend of 85% ethanol and 15% gasoline. This blend is intended to reduce dependence on fossil fuels and lower greenhouse gas emissions.

In emissions testing and regulations, ethanol's role as an alternative fuel is significant since it can contribute to cleaner combustion compared to pure gasoline. Therefore, identifying gas and ethanol as the correct combination highlights the relevance of understanding various fuel types when conducting emissions inspections and recognizing their impacts on emissions levels.

Other fuel types mentioned in the options, while important in the broader context of vehicle emissions, do not specifically align with the training focus on the combination of gasoline and ethanol as a current consideration in emission standards and testing methodologies.