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
[{'content': 'The commonest site of diveiculosis is: \nSelect and explain. \nA. Ascending colon, B. Transverse colon, C. Descendin gcolon, D. Sigmoid colon', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Sigmoid colon', 'role': 'assistant'}]