This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastro Intestinal System, Subject name: Pediatrics
[{'content': 'Congenital mega colon is confirmed by: \nSelect and explain. \nA. Rectal biopsy, B. Sigmoidoscopy, C. Barium enema, D. Invertogram', 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Rectal biopsy(Ref: Nelson's 20/e p 1894-1897Ghai 8/e p 285-286)Congenital Aganglionic Megacolon is the other name for Hirschsprung diseaseDiagnosis of Hirschsprung disease is confirmed by rectal biopsy.", 'role': 'assistant'}]