The factors of production include

In the case of heterogeneous causal effects, the following is not true:

A) in the circumstances in which OLS would normally be consistent (when E(ui Xi) = 0), the OLS estimator continues to be consistent. B) OLS estimation using heteroskedasticity-robust standard errors is identical to TSLS. C) the OLS estimator is properly interpreted as a consistent estimator of the average causal effect in the population being studied. D) the TSLS estimator in general is not a consistent estimator of the average causal effect if an individual's decision to receive treatment depends on the effectiveness of the treatment for that individual.

Because of the free-rider problem:

A. the market demand for a public good is overstated. B. the market demand for a public good is nonexistent or understated. C. government has increasingly yielded to the private sector in producing public goods. D. public goods often create serious negative externalities.