Which of the Following Best Explains Why a Certain Amount

Which of the following best explains why a certain amount of unemployment may be socially desirable?

A) When some workers become unemployed it provides a chance for others in the labour force to become employed.
B) Unemployed workers are able to benefit from employment insurance.
C) The time spent unemployed by the worker is valuable for finding the most appropriate match with firms.
D) A pool of unemployed workers drives down the average wage in the economy,and keeps workers from becoming greedy.
E) A pool of unemployed workers provides an incentive to those employed to remain productive.