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.