This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Circulation: Heart Valves and Heart Sounds;  Heart Defects, Subject name: Physiology
[{'content': 'Dicrotic notch corresponds to? \nSelect and explain. \nA. Closure of AV valves, B. Closure of Aortic and pulmonic valves, C. Opening of AV valves, D. Opening of Aortic and pulmonic valves', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Closure of aortic and pulmonic valvesRef.: Ganottg 25th ed. 1540The Dicrotic notch is small oscillations on the falling phase of the pulse wave caused by vibrations set up when the aortic valve snaps shut.', 'role': 'assistant'}]