Many Economists Argue That the Unemployment Rate Tends to Understate

Many economists argue that the unemployment rate tends to understate the actual amount of unemployment. Why?

A) The unemployment rate excludes persons who work in the service sector.
B) The unemployment rate excludes persons who are unable to find work.
C) The unemployment rate excludes persons who want to work but have given up looking for a job.
D) The unemployment rate excludes workers who are also students.