Which one of the following statements is correct concerning unsystematic risk?

a. An investor is rewarded for assuming unsystematic risk.

b. Beta measures the level of unsystematic risk inherent in an individual security.

c. Standard deviation is a measure of unsystematic risk.

d. Eliminating unsystematic risk is the responsibility of the individual investor.

e. Unsystematic risk is rewarded when it exceeds the market level of unsystematic risk.