Final answer:
Grandfathered coal-burning plants are required to regulate toxic emissions, adhering to legal standards set by government, which is a form of command-and-control regulation. Option D is correct.
Step-by-step explanation:
Starting in 2012, "grandfathered" coal-burning plants must regulate toxic emissions. This falls under command-and-control regulation, which has been a common approach in the United States since the environmental laws of the late 1960s and early 1970s.
These laws set limits on emissions and required the installation of anti-pollution equipment. While options like 'mitigate' or 'sequester' deal with reducing or storing emissions, 'regulate' is the term that usually applies to the legal requirement to adhere to specific governmental standards for emissions.
Additionally, carbon capture and sequestration is a technique for addressing carbon dioxide emissions, and it represents an ongoing research area rather than a regulatory requirement.
This includes setting emissions limits and mandating anti-pollution equipment.