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: Pharmacology
[{'content': 'Orphan drugs are: \nSelect and explain. \nA. Drugs with high therapeutic failure, B. Drugs with high toxicity, C. Drugs having low therapeutic margin, D. Drugs for rare disease', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]