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 not a feature of cardiac muscle? \nSelect and explain. \nA. Tetany, B. All or none phenomenon, C. Pacemaker potential, D. Length-tension relationship', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Tetany is not possible in cardiac muscle due to long refractory period', 'role': 'assistant'}]