Correct Option: C

An ad valorem tax (Latin for "according to value") is a tax based on the value of real estate or personal property. It is more common than a specific tax, a tax based on the quantity of an item, such as cents per kilogram, regardless of price. It is levied on the basis of value given by producers. So sometimes, the primary difficulty with such taxation, especially in the case of tariffs, is in establishing a satisfactory value figure.