Which of the Following Statements About Frictional Unemployment Is Most

Which of the following statements about frictional unemployment is most accurate?

A) Its source is a mismatch between the needs of employers with job vacancies and the unemployed workers.
B) Its source is that unemployed workers and the employers with job vacancies have not yet found each other.
C) It exists when only there are no jobs for the unemployed people in the economy.
D) The only way to reduce it is to shift the AD curve to the left.
E) The only way to reduce it is to shift the AD curve to the right.