In the Cambridge version of the Quantity Theory of Money, the amount of real money balances __________ after an increase in the nominal money supply

At the optimal or efficient level of an activity, the activity's marginal benefit must

A) be zero. B) be greater than zero. C) equal the marginal cost of the activity. D) exceed the marginal cost of the activity.

Market failures include all of the following EXCEPT

A) buyers pay for all the costs involved in the production of goods and services. B) public goods. C) positive externalities. D) negative externalities.