Flu Shots Provide a Positive Externality

Multiple Choice

Flu shots provide a positive externality. Suppose that the market for vaccinations is perfectly competitive. Without government intervention in the vaccination market, which of the following statements is correct?

A) At the current output level, the marginal social benefit exceeds the marginal private benefit.
B) The current output level is inefficiently low.
C) A per-shot subsidy could turn an inefficient situation into an efficient one.
D) All of the above are correct.