Under which of the following conditions would increasing the age at which people become eligible for Medicare make sense?

a. if life expectancy decreases
b. if life expectancy increases
c. if Medicaid expands to include a greater number of people
d. if the Affordable Care Act, colloquially known as Obamacare, is repealed
e. if the Affordable Care Act, colloquially known as Obamacare, is strengthened

b