It Has Been Suggested That Stress and Personality Factors Have

It has been suggested that stress and personality factors have indirect effects on the risk of heart attack and stroke. What does this mean?

A) Those factors are correlated with risk, but are also correlated with other risk factors like smoking or poor diets.
B) The effects of those factors are very small, and although they are interesting they don't predict much about health.
C) Those factors only have effects in people who have a genetic predisposition toward cardiovascular problems.
D) If those factors are removed from analysis, we are unable to predict who is at risk for those illnesses.