What term describes a payment demanded for the release of a prisoner?

The correct term that describes a payment demanded for the release of a prisoner is ransom. This term specifically refers to a sum of money or other payment that is requested or paid in exchange for the freedom of someone who has been captured or held against their will. The concept of ransom is often linked to kidnappings or hostage situations, where the captors demand payment as a condition for releasing the hostage.

Tribute money refers to payments made by one state or ruler to another as a form of acknowledgment of submission or for protection, but it does not pertain specifically to the release of an individual. A tariff is a tax imposed on imported goods, which again does not relate to the context of prisoner release. Lastly, a tax is a compulsory financial charge by a government on its citizens, and while it involves payments, it does not involve the conditions of payment associated with liberation of a captive. Thus, ransom is the appropriate term for this situation.