This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
[{'content': 'Least common about angiodysplasia of colon: \nSelect and explain. \nA. Involvement of cecum, B. Involvement of rectum in 50% of cases, C. Affecting age group more than 50 years only, D. Cause of troublesome lower GI hemorrhage', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Involvement of rectum in 50% of casesRef: Sabiston 20th edition, Page 1153Angiodysplasia of colon:* Arteriovenous Malformations of bowel* Equal in both sexes* Affects age group >50 years only* Produced massive bleeding from colon in 15% and it is troublesome in diagnosing.* Bleeding stops spontaneously in most of them but recurs* Most common site is ascending colon and cecum* Least common in rectum* Treated by endoscopic coagulation or sclerosing agent or intrarterial embolization.* Surgical resection is done if not stops -- colectomy.', 'role': 'assistant'}]