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: Physiology
[{'content': 'Which of the following is the mechanism for a decrease in splanchnic blood flow during exercise? \nSelect and explain. \nA. Venoconstriction with decreased blood flow, B. Venodilation with decreased blood flow, C. Venodilation with increased blood flow, D. Venodilation with normal blood flow', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Constriction of splanchnic vessels may increase volume of blood actively circulating and this may help in perfusing the muscles by as much as 30%.', 'role': 'assistant'}]