Based on Schaie's Findings About Cognitive Decline with Age, What

Based on Schaie's findings about cognitive decline with age, what can be concluded?

A) Cognitive abilities decline regardless of social class or financial status.
B) Cognitive abilities tend not to decline with age.
C) The richer one is and the higher one's social class, the less one's cognitive abilities decline.
D) Cognitive abilities decline at a rate determined by genetics.