When there is a positiveexternalityin the market for a good, which of these statements is true? (choose all the correct answers)

Firms set theirmarginal private cost equal to the marginal external cost.

The social planner setsmarginal social benefit equal tofirms' marginal cost.

The private market tends to produce less than is socially efficient.

Production of this good should be banned.

The private market tends to produce more than is socially efficient.