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: Pediatrics
[{'content': 'By what age a child can make tower of 3 cubes? \nSelect and explain. \nA. 15 months, B. 18 months, C. 24 months, D. 28 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: 15 months - 2 cube tower\n18 months - 3 cube tower\n24 months - 6 cube tower\n36 months - 9 cube tower', 'role': 'assistant'}]