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': 'What is true about ulcerative colitis? \nSelect and explain. \nA. Involves rectum and then whole colon backwards, B. Involves only colon, C. Skip lesions seen, D. Ileum not involved', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Involves rectum and then whole colon backwards o Ulcerative colitis involves the rectum and extends proximally in a retrograde fashion to involve the entire colon (pancolitis) in more severe cases.", 'role': 'assistant'}]