Which of the Following Has Not Been Revealed by Research

Which of the following has not been revealed by research on the relationship between optimism and health?

A) Optimists are more likely than pessimists to make a quicker and fuller recovery from coronary artery bypass surgery.
B) A positive correlation exists between hopelessness and mortality.
C) Optimism can have negative consequences when it leads people to believe that they have control over uncontrollable events.
D) Optimists are more likely than pessimists to take an emotion-focused approach to dealing with stress.