Which one of the following statements correctly describes a public policy approach to addressing an environmental problem? A. Setting and enforcing a limit on air pollution emissions is an example of a regulatory (command-and-control) policy approach. B. Setting and enforcing a drinking water quality standard is an example of a free market-based policy approach. C. Introducing an invasive species into an environment to increase competition for resources is an example of a command-and-control public policy approach. D. Providing a polluter with an economic dis-incentive to emit pollution into the environment is an example of a regulatory (command-and-control) policy approach.