Which statement about crude and age-adjusted rates is true? Question 15 options: a) Since 1980, the age-adjusted death rate in the United States has declined more steeply than the crude death rate. b) In 2013, the age-adjusted death rate in the United States was higher than the crude death rate. c) Higher crude death rates in some U.S. states are a reflection of younger populations in those states. d) The standard U.S. population for age adjustment is the U.S. population in the year 1940