The aim of the study in the Journal of the American Geriatrics Society is

A、toseewhetherpeople'spersonalityaffectstheirlifespar
B、tofindoutifone'slifestylehasanyeffectontheirhealth
C、toinvestigatetheroleofexerciseinlivingalonglife
D、toexamineallthefactorscontributingtolongevity