What are the two key concepts for this section? Describe three ways in which economists estimate the economic values of natural goods and services. Why are such values not included in the market...

What are the two key concepts for this section? Describe three ways in which economists estimate the economic values of natural goods and services. Why are such values not included in the market prices of goods and services? Define discount rate and explain the controversy over how to assign such rates. What is a marginal cost? Explain how economists can estimate the optimal levels for pollution control and resource use. Define cost–benefit analysis and list its advantages and limitations.