The comparative advantage in a specific good can shift over time from one country to another, as the other countries can produce it at a cheaper cost after imitating the technology

In the ________________ of externalities, the market equilibrium is ______________ efficient because it maximizes the net social benefit.

a. absence; ecologically b. presence; ecologically c. absence; economically d. presence; economically e. absence; environmentally

Suppose a monopoly sells to two identifiably different types of customers, A and B, who are unable to practice arbitrage. The inverse demand curve for group A is PA = 10 - QA, and the inverse demand curve for group B is PB = 18 - QB. The monopolist is able to produce the good for either type of customer at a constant marginal cost of 2, and the monopolist has no fixed costs. If the monopolist is

able to practice group price discrimination, the values of the elasticities of the two groups at the profit-maximizing prices are A) ?A = -1.25, and ?B = -1.5. B) ?A = -1.5, and ?B = -1.25. C) ?A = -0.67, and ?B = -0.8. D) ?A = -0.8, and ?B = -0.67.