This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolic Disorders, Subject name: Pediatrics
[{'content': "Earliest sign of rickets is: \nSelect and explain. \nA. Rickety rosary, B. Craniotabes, C. Boe legs, D. Harrison's groove", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans: bRef: Pedia ghai, 6th ed, p. 128', 'role': 'assistant'}]