This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
[{'content': 'Which of the following OCD carries worst prognosis to treatment? \nSelect and explain. \nA. Pathological doubt, B. Contamination, C. Hoarding disorder, D. Obsessive thought disorder', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Hoarding disorder is characterized by acquiring and accumulating useless things\xa0attaching them with emotional importance.\nExposure and response prevention which is a standard treatment for OCD, is often found ineffective and hence it carries worst prognosis.', 'role': 'assistant'}]