This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Growth, Development, and Behavior, Subject name: Pediatrics
[{'content': 'Toilet training should be started at what age? \nSelect and explain. \nA. 2 years, B. 3 years, C. 4 years, D. 5 years', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. 2 yearsToilet training should be started after 2 years of age, when the child has spontaneously started indicating bladder and bowel fullness and is able to follow simple instructions.', 'role': 'assistant'}]