8. Which of the following is a correct?

a. Frictional unemployment is not inevitable; rather, it can be reduced to zero by well-designed public policies.

b. Frictional unemployment is not inevitable; rather, it could be reduced to zero if by the elimination of unemployment insurance.

c. Frictional unemployment is inevitable, because at any given time, jobs are being created in some firms and destroyed in other firms. d. Frictional unemployment is inevitable, because in some industries, wages are always set above the level that brings supply and demand into equilibrium.