This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart, Circulation, and Blood, Subject name: Physiology
[{'content': 'Plateau phase of cardiac cycle is due to - \nSelect and explain. \nA. Na+, B. K+, C. Ca2+, D. Cl-', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., Ca2+ o Phase 0 (phase of rapid depolarization)- opening of fast sodium channels with Na4 influxo Phase 1 (initial phase of rapid repolarization)- closure of fast sodium channelso Phase 2 (plateu phase)- opening of voltage gated slow Ca++ channels with calcium influx.o Phase 3 (final repolarization)- opening of K+ channels with K+ efflux.o Phase 4- Resting membrane potential.", 'role': 'assistant'}]