Problem: A third-year medical student returned to the student-health services for a third time thinking he has ulcerative colitis. After a thorough medical work-up, he was told that no organic disease was present. Despite that reassurance, the student continued to test his stool for blood and continued to believe that his physicians had missed the correct diagnosis. The student is exhibiting Group of answer choices Somatic Symptom Disorder colitis Conversion disorder Illness Anxiety Disorder