【正确答案】 C

【答案解析】There are only three types of unemployment: frictional, cyclical, and structural. Frictional unemployment is due to constant changes in the economy that prevent qualified workers from being immediately matched with existing job openings. Cyclical unemployment is when the economy is operating at less than full capacity. Structural unemployment is due to structural changes in the economy that eliminate some jobs while generating job openings for which unemployed workers are not qualified.