Which of the following correctly describes the external benefit resulting from an individual's purchase of a winter flu shot?

A. The flu shot is cheaper than the cost of treatment when you get the flu.
B. The income of doctors increases when you get the flu shot.
C. The flu shot reduces the likelihood others will catch the flu.
D. The flu shot reduces the likelihood you will miss work as the result of sickness; therefore, you will earn more income.

Answer: C