An 18.4 cent tax on every gallon of gasoline sold is an example of a(n) tax (one word).

The 18.4 cent tax on every gallon of gasoline sold is an example of an excise tax. An excise tax is a type of tax imposed on specific goods and services, which often targets items like fuel, tobacco, and alcohol. This tax is usually included in the price of the product and may be used to raise revenue for specific purposes, such as funding transportation infrastructure or public health initiatives. Excise taxes can affect consumer behavior, as they typically lead to higher prices for the taxed goods, which may reduce consumption. In the case of gasoline, the excise tax can also serve as an incentive to encourage the use of more fuel-efficient vehicles or alternative energy sources.