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
[{'content': 'In villous papilloma of rectum which is lost \nSelect and explain. \nA. Na+, B. K+, C. Ca++, D. Cl-', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Villous adenomas of rectum These have a characteristic frond-like appearance. They may be very large, occupying much of the circumference of the rectum. These tumours have an increased tendency to become malignant. Rarely, the profuse mucus discharge from these tumours, which is rich in potassium, causes electrolyte and fluid losses Ref: Bailey and love 27th edition Pgno : 1326', 'role': 'assistant'}]