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: Pathology
[{'content': 'Which of the following gene is responsible for Fibrous dysplasia: \nSelect and explain. \nA. GNAS1, B. GNAS2, C. GNAS3, D. GNAS4.', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]