Which Statement Is TRUE About Research on the Extremes of Memory

Which statement is TRUE about research on the extremes of memory impairment and memory excellence?

A) Research has found that memory impairment is due primarily to Alzheimer's disease.
B) Much of the research that psychologists conduct on memory falls between the two extremes.
C) Research reveals that memory excellence depends primarily on inborn ability.
D) Memory impairment and memory excellence are the primary focal points of memory research.