Which of the Following Factors Has Contributed to Rising Health

Which of the following factors has contributed to rising health care prices in the United States?

A) The supply of physicians per 100,000 people has decreased since 1975.
B) Productivity growth in the health care industry has been negative in recent years.
C) Improvements in medical technology have significantly increased the number of patients that can be treated each year.
D) The supply of physicians per 100,000 people has risen since 1975, but not as fast as the increase in the demand for physicians' services.