This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Intestinal obstruction, Subject name: Surgery
[{'content': 'True about strangulation of intestine is: \nSelect and explain. \nA. Aerial blood flow affected first, B. Usually venous blood flow affected first, C. Blood flow normal, D. No gangrene', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Venous return is compromised before aerial supply in strangulated intestinal obstruction.', 'role': 'assistant'}]