This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
Investigation of choice in hirschsprung disease is - 
Select and explain. 
A. Biopsy, B. Manometry, C. Colonoscopy, D. Barium enema
A: Biopsy
Answer: A: Biopsy 
Explanation: Ans. is 'a' i.e., Biopsy * The investigation of choice for diagnosis requires an adequate rectal biopsy and an experienced pathologist.* A contrast enema may show the narrow aganglionic segment, a cone and the dilated proximal bowel.