With Regard to Intelligence and Age, Researchers Have Found That

With regard to intelligence and age, researchers have found that _____.

A) intelligence shows a marked decline around age 60 in cross-sectional studies
B) intelligence peaks in early adulthood, then gradually declines in longitudinal studies
C) reasoning and intelligence reach their peak in early adolescence and then gradually decline in cross-sectional studies
D) reasoning and intelligence reach their peak in early adulthood and then gradually decline in cross-sectional studies