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': 'The first centres of ossication appears during which month of pregnancy? \nSelect and explain. \nA. At the end of 2 month of pregnancy, B. At the beginning of 3rd month of pregnancy, C. At the end of 3rd  month of pregnancy, D. At the end of 4th month of pregnancy', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]