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: Surgery
Investigation of choice in Hirschsprung's disease is 
Select and explain. 
A. Barium swallow, B. CECT, C. Barium enema, D. Rectal biopsy
D: Rectal biopsy
Answer: D: Rectal biopsy 
Explanation: Rectal biopsy is defn diagnosis. Affected part has no ganglions.