economics is hard, any help with this?

[clogos]

its open book so this isnt cheating. im just having tons of trouble.

89. Because monopolistically competitive firms charge a P > MC ______. (Points: 3)
monopolistic competition is efficient
monopolistic competition is inefficient
the marginal benefit to society of an additional unit of output is below its cost
B and C are true


90. If a coal-powered electrical generator discharges smoke into the air and causes uncompensated costs and discomfort to residents of a town, this situation is an example of a(n) ______. (Points: 3)
quasi-public good
external cost
external benefit
specific tax


91. According to the Coase theorem, when negative externalities are present, a market will ______. (Points: 3)
always reach an efficient solution
reach an efficient solution if transaction costs are low
reach an efficient solution only if the government intervenes in the market
reach an efficient solution only if the negative externalities are offset by positive externalities


92. Which of the following is usually associated with a positive externality? (Points: 3)
smoking cigarettes
purchasing a new CD
innovation in the semiconductor industry
all of the above