Which type of occupation earned the lowest average wage in 2016?

When external costs are present and the government imposes a tax equal to the marginal external cost, then

A) efficiency can be achieved. B) transaction costs will be high. C) the marginal benefit of the external cost will fall. D) property rights must have already been established.

United States net unilateral transfers have been

a. positive every year since 1950 b. negative every year since 1950 c. positive every year since 1950 except 1991, during the Persian Gulf War d. negative every year since 1950 except 1991, during the Persian Gulf War e. positive about half the time and negative about half the time since 1950