Correct Answer: Unemployment caused by changes in the business cycle.

Solution : The correct answer is (a) Unemployment caused by changes in the business cycle.

The concept of "cyclical unemployment" refers to unemployment that is caused by changes in the business cycle or economic fluctuations. It occurs when there is a downturn or recession in the economy, leading to a decrease in aggregate demand and a decline in production and employment. During such periods, businesses may reduce their workforce or implement layoffs due to decreased demand for goods and services. Cyclical unemployment is considered a temporary type of unemployment and is closely tied to the overall health of the economy. As the economy recovers and expands, cyclical unemployment tends to decrease as businesses increase their hiring and production levels.