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: Anaesthesia
[{'content': 'Chest compression during CPR depth: March 2013 (a, c, d, g) \nSelect and explain. \nA. 1 inch, B. 2 inches, C. 3 inches, D. 4 inches', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B i.e. 2 inches', 'role': 'assistant'}]