Which of the following terms describes a rapid and severe decrease in the purchasing power of a currency?

The correct term for a rapid and severe decrease in the purchasing power of a currency is hyperinflation. Hyperinflation occurs when there is an excessive and accelerated increase in prices, often resulting from a significant increase in the money supply not supported by economic growth. This leads to a situation where the value of money collapses, making it necessary for consumers to spend large quantities of money to purchase basic goods and services, effectively eroding their purchasing power.

Other terms such as deflation, recession, and depression describe different economic phenomena. Deflation refers to a general decrease in prices, usually suggesting an increase in the value of currency rather than a decrease in purchasing power. A recession is a period of economic decline characterized by reduced economic activity, often resulting in decreased demand and output, but does not inherently imply a rapid decline in purchasing power. A depression is a much more severe and prolonged economic downturn than a recession, typically associated with high unemployment and a significant fall in spending, but again, it is not defined by the rapid loss of purchasing power in the same way that hyperinflation is.