Which concept is essential for understanding the quantity of care consumed, revenues paid and received, and distribution of costs between patients and insurers for the different payment schemes discussed in this module?

A) The price patients pay for care and their demand for care

B) The cross-price elasticity of demand between the price of gasoline and the quantity of healthcare consumed

C) The production possibility frontier and the impact that healthcare spending has on the country's ability to afford other goods and services

D) Per capita healthcare spending in the US and the relative payoff in terms of life expectancy at birth.

Please give explanation