The graph shows changes in life expectancy in the United States over a fifty-year period. What challenge arose as a result of the trend shown above?
A. educating millions of school-age children
B. providing medical care for an aging population
C. keeping people from leaving the country to retire overseas
D. offering easy-to-follow voting registration procedures

I believe the answer would be "B"

Explanation: if you're able to provide better medical care for the aging population then they can live longer therefore the more aging people treated the higher the life expectancy is

I think it is --- providing medical care for an aging population

Explanation:

The question is asking about challenges that came from life expectancy rising, with a longer life expectancy there's going to be an aging population. the other options are don't really fit as we're talking about old ppl not children, old ppl will have already been registered to vote

d. japan's attack on pearl harbor

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.