What Problem Is Associated with Studying People Who Survive Their

What problem is associated with studying people who survive their suicide attempt to understand the reasons for why a person commits suicide?

A) Attempters are more likely to be adolescents.
B) Attempters are more likely to have good skills in conflict resolution.
C) People who succeed in ending their lives most likely died of a drug overdose.
D) People who survive suicide attempts differ from those who are successful in their attempt.