Which of the Following Is an Example of a Potential

Multiple Choice

Which of the following is an example of a potential shared, "age-graded" change in adulthood?

A) a loss of fitness (e.g., aerobic capacity) beginning in the 30s and 40s and continuing into old age
B) a decrease in the frequency of contact with siblings between middle age and old age
C) a lower average number of years of education among current 25-year-olds than among current 65-year-olds
D) a lesser susceptibility to disease among current 65-year-olds than among current 30-year-olds