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': 'A pharmaceutical agent that has been developed specifically to treat a rare medical condition (affecting fewer than 200,000 people): \nSelect and explain. \nA. Orphan Drug, B. Primary Drug, C. Rare Drug, D. Pioneer Drug', 'role': 'user'}, {'content': 'Answer: A \nExplanation: An orphan drug is a pharmaceutical agent that has been developed specifically to treat a rare medical condition (affecting fewer than 200,000 people).', 'role': 'assistant'}]