In Trying to Determine If the Type A/Type B Classifications

In trying to determine if the Type A/Type B classifications are reliable and valid as predictors of heart disease,it becomes apparent that

A) not every individual shows distinctively Type A or Type B characteristics.
B) women are usually Type A and men are usually Type B.
C) interviews to assess people's personality characteristics are more reliable than questionnaires.
D) medical tests are the only valid predictors of heart disease.