In 2006, the nation of Zimbabwe reduced the value of its currency by 60 percent to bring its value more in line with the relative value of most other world currencies. This reduction of value is called

C. devaluation

Explanation:

Devaluation of a currency is the term used to describe the reduction of a currency's value by the authority that produces said currency.

It is done deliberately and is usually done to strengthen a country's balance of trade because the exports of the country will become cheaper which will increase the demand for it.

By reducing the value of their currency themselves, the nation of Zimbabwe devalued their currency in 2006.