Final answer:
The correct statement is: c. If physicians are earning monopoly rents, then there must be more barriers to entry in the labor market for physicians than is socially optimal.
Step-by-step explanation:
Monopoly rents refer to the extra earnings that a business can make by controlling a market with little or no competition. In the case of physicians, if they are earning monopoly rents, it suggests that there are barriers to entry in the labor market for physicians.
These barriers can include high education and training costs, licensing requirements, limited residency spots, and restrictions on foreign-trained physicians. These barriers limit the number of physicians entering the market, leading to higher prices and less efficiency in the healthcare industry.