This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Average head circumference at bih is ? \nSelect and explain. \nA. 35 cm, B. 40 cm, C. 45 cm, D. 50 cm', 'role': 'user'}, {'content': 'Answer: A \nExplanation: O.P. Ghai 9th ed, page 14 Beginning at 34 cm at bih, the head circumference increases approximately 2 cm per month for first 3 months, 1 cm per month from 3-6 months and 0.5 cm per month for rhe rest of the first year of life.', 'role': 'assistant'}]