The life expectancy in the United States increased more than 30% from 1930 to 2015. Which factor could have contributed to this increase?

A - better medical facilities and treatments

B - decreased farmland

C - increased food insecurity

D - refusal of vaccines

The life expectancy in the United States increased more than 30% from 1930 to 2015 is likely because of the better medical facilities and treatments. Advanced technology and newly discovered treatments for fatal illnesses contibute much to life expectancy in the United States.