Which of the Following Studies Most Clearly Has the Directionality

Multiple Choice

Which of the following studies most clearly has the directionality problem?

A) a study on whether or not a person was sexually abused as a child and how paranoid he or she is as an adult
B) a study on the relationship between losing a limb and one's self-esteem
C) a study relating college students' study habits to their final exam performance
D) a study on the correlation between how much negative emotion a person has and how many physical symptoms he or she has