The Meaning of Age-Adjusted Death Rate an Age-Adjusted Death Rate

The meaning of age-adjusted death rate An age-adjusted death rate in the U.S.in 2010 of 746.2 per 100,000 compared to the age-adjusted death rate of 860 in 2000 means that:

A) the lifespan is showing a gradual increase per decade.
B) the population is getting healthier because people are dying at later ages.
C) fewer people overall were dying in 2010 than in 2000.
D) the population is getting unhealthier because people are dying at younger ages.