This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal obstruction, Subject name: Surgery
A patient has presented with carcinoma rectum with obstruction in emergency. What is the treatment of choice? 
Select and explain. 
A. Haman's Procedure, B. Total colectomy, C. Left hemi-colectomy, D. Defunctioning colostomy
D: Defunctioning colostomy
Answer: D: Defunctioning colostomy 
Explanation: Most common site of colorectal cancer is rectum, in obstructing carcinoma rectum loop colostomy or defunctioning colostomy should be done to relieve obstruction followed by neoadjuvant chemoradiation, with the plan to resect the primary lesion at a later time.