Many People Who Have Undergone Critical Incident Stress Debriefing (CISD)

Many people who have undergone Critical Incident Stress Debriefing (CISD) claim that they are satisfied with it. What is wrong with relying on such self-reports to assess the effectiveness of CISD?

A) People cannot know how they would have responded without CISD.
B) People are probably just lying on the survey.
C) People are so traumatized they cannot accurately self-report.
D) People usually just report what they think the researcher wants to hear.