If the government implements a price ceiling on insulin, this will have all of the following effects on the market for insulin except

Assume good X is produced in a monopolistically competitive market. In addition, each of the firms in the industry uses essentially the same technology. Competitors distinguish their individual products primarily through persuasive advertising

Assume that one of the firms in the market discovers a new production process that substantially reduces the average costs of production. Analyze the effects of this discovery on long-run equilibrium in the market.

Which of the following statements is correct?

a. The use of pollution permits and corrective taxes reduces the cost of environmental protection. b. Rich countries usually have cleaner environments than poor countries because a clean environment is like other normal goods in that it has a positive income elasticity. c. Clean water and clean air are goods to which the law of demand applies. d. All of the above are correct.