Economics Homework Help!! pleAse help (multiple choice)?

[JustWondering]

these are questions i cannot find the answer to so you help is greatly appreciated.

24.Does economic efficiency indicate that all pollution should be eliminated?
a.No, at some point, the benefits of still lower levels of pollution will not be worth the additional cost.
b.No, pollution does not harm most people, and therefore, we should not worry about it.
c.Yes, pollution is bad; it harms both people and the environment, and therefore, it should be eliminated.
d.Partially, pollution caused by business firms should be eliminated, but people should still be allowed to pollute if they want.

25.A good is considered nonrival-in-consumption (or joint in consumption) if
a.even nonpaying customers can receive the full benefit from the good.
b.the consumption of the good by one individual lowers the amount available for others.
c.many individuals can share in the consumption of the same unit of the good.
d.its production is financed through tax revenue rather than market prices