Final answer:
C. supply-side
The growth of the U.S. economy in the 1980s is attributed to the principles of supply-side economics, which focuses on lower tax rates to improve work incentives, as promoted by President Reagan and his advisors.
Step-by-step explanation:
According to supply-side economists, the growth of the U.S. economy in the 1980s can be attributed to lower marginal tax rates which improved the incentives for people to work.
Supply-side economics is an economic theory that suggests government policies should focus on reducing taxes and regulations to stimulate production and economic growth, contrasting with Keynesian economics that emphasizes government spending and demand stimulation.
President Reagan and his economic advisors were proponents of this approach during the 1980s.
They advocated for tax cuts based on the belief that lower taxes would motivate individuals to work more, leading to an increase in the supply of labor and potentially increasing the country's productive capacity and economic output.