The Official Unemployment Rate May Not Reflect the True State

The official unemployment rate may not reflect the true state of unemployment because:

A) part-time employees who want to work more hours are treated the same statistically as those who hold full-time jobs.
B) some individuals who want to work may become discouraged and cease actively looking for work.
C) workers laid off from their jobs and looking for new ones are not counted among the unemployed.
D) of (a) and (b) only.