This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
The rectum measures 
Select and explain. 
A. 18 cm, B. 22 cm, C. 17 cm, D. 15 cm
D: 15 cm
Answer: D: 15 cm 
Explanation: The adult rectum is approximately 12-18 cm in length and is conveniently divided into three equal pas: the upper third, which is mobile and has a peritoneal coat; the middle third where the peritoneum covers only the anterior and pa of the lateral surfaces; and the lowest third, which lies deep in the pelvis surrounded by fatty mesorectum and has impoant relations to fascial layers. Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1219