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, does the child develops the following developmental milestone? \nSelect and explain. \nA. 8 months, B. 9 months, C. 10 months, D. 12 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: This is Object Permanence - Develops by 9 months of age.\nWhen the baby loses object while playing. Knows that it is somehwere around.', 'role': 'assistant'}]