One difference between sales and excise taxes is that

a. sales taxes are only applied at the state level, while excise taxes are only applied at the federal level.

b. excise taxes apply to a wide range of products, while sales taxes apply only to a select list of products.

c. sales taxes are calculated as a percentage of the price paid, while excise taxes are levied on a per-unit basis.

d. excise taxes are calculated as a percentage of the price paid, while sales taxes are levied on a per-unit basis.