This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
[{'content': 'The plateau phase of Myocardial action potential is due to \nSelect and explain. \nA. Efflux of Na+, B. Influx of Ca++, C. Influx of K+, D. Closure of voltage gated K+ channels', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ca2+ influx through more slowly opening Ca2+ channels produces the plateau phaseRef: Ganong's Review of Medical Physiology Twenty-Third Edition Page No: 491", 'role': 'assistant'}]