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': 'The skeletal muscle action potential: \nSelect and explain. \nA. Is not essential for contraction to occur, B. Has a prolonged plateau phase, C. Spreads in ward to all parts of the muscle via the T-tubule system, D. Begins with an inward movement of K+ ion', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]