This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Developmental-Behavioral Screening and Surveillance, Subject name: Pediatrics
[{'content': 'A baby placed in the prone position is able to lift the head and upper chest on extended arms by? \nSelect and explain. \nA. 1 month, B. 3 months, C. 6 months, D. 9 months', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) 6 MonthsRef: OP Ghai 8th ed./154* Head lag disappears by 3 months* Head control is achieved by 4 months* A child in prone position at 3 months can lift chin off the bed, but it takes a while for the shoulder muscles to develop sufficient strength so as to lift the chest and head off the bed. This activity would be possible by 6 months* Wave bye-bye by 9 months* Stand without support at 12 months* And can run by 18 months', 'role': 'assistant'}]