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': 'A 7 - year - old boy underwent neurosurgery for craniopharyngioma following which pituitary functions were lost. Which of the following hormone should be replaced first? \nSelect and explain. \nA. Hydrocortisone, B. Thyroxine, C. Growth hormone, D. Prolactin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Hydrocortisone, followed by GH is vital to be given in a child with lost pituitary function.', 'role': 'assistant'}]