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: Anatomy
[{'content': 'Autonomic supply to S.A node is - \nSelect and explain. \nA. Parasympathetic excitatory, B. Sympathetic excitatory, C. Both excitatory, D. Both inhibitory', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sympathetic supply to heart excites the cardiac activity to increase the heart rate and contractility.', 'role': 'assistant'}]