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: Pathology
Which among the following is the commonest site of diveiculosis in old population? 
Select and explain. 
A. Ascending colon, B. Transverse colon, C. Descending colon, D. Sigmoid colon
D: Sigmoid colon
Answer: D: Sigmoid colon 
Explanation: Diveiculosis refers to the presence of diveicula without inflammation. The sigmoid colon is the most common site of diveiculosis. The majority of colonic diveicula are false diveicula in which the mucosa and muscularis mucosa have herniated through the colonic wall. These diveicula occur between the taeniae coli, at points where the main blood vessels penetrate the colonic wall (presumably creating an area of relative weakness in the colonic muscle). Ref: Bullard Dunn K.M., Rothenberger D.A. (2010). Chapter 29. Colon, Rectum, and Anus. In F.C. Brunicardi, D.K. Andersen, T.R. Billiar, D.L. Dunn, J.G. Hunter, J.B. Matthews, R.E. Pollock (Eds), Schwaz's Principles of Surgery, 9e.