Final answer:
The command-and-control policy is the approach where the U.S. government mandates the use of predetermined technologies for reducing CO2 emissions. The alternate approach, which involves government subsidies for cleaner technologies, represents a market-based strategy that encourages innovation and voluntary compliance.
Step-by-step explanation:
When considering two basic approaches for efficiency-improving government intervention, the first approach where the U.S. government mandates the use of predetermined technologies is known as a command-and-control policy. This type of policy requires specific actions by industry and typically provides less flexibility for individual enterprises. On the other hand, the second approach where the government subsidizes cleaner technologies represents a more market-based strategy, offering incentives for businesses to innovate and reduce emissions voluntarily.
These approaches reflect different strategies for the government to intervene in the economy to achieve environmental goals. The command-and-control approach tends to be more prescriptive, while market-based interventions such as subsidies stimulate economic entities to find cost-effective solutions to reduce emissions themselves. Both have their merits and can play a role in a comprehensive environmental policy.