According the coase theorem, the private sector can achieve social efficiency if the government: select one: a. establishes and enforces property rights. b. imposes taxes to serve as proxies for external costs. c. set rigorous environmental standards. d. encourages competition with antitrust laws.

The correct answer is letter A.

Coase Theorem is a concept created by the British economist Ronald Coase in his 1937 article The Nature of the Firm.

Coase explains that "firms" are organized to operate in the markets in order to reduce transaction costs that are those incorporated by third parties in economic market negotiations (information costs, contract costs.). In other words, for the creator of this theory, economic agents do not act directly in the market, companies are created and structured to do so.

sumerians were polytheistic, meaning they believed in many different gods. so, the best answer is c.