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: Medicine
[{'content': 'The dicrotic notch on the aortic pressure curve is caused by - \nSelect and explain. \nA. Closure of the pulmonary valve, B. Rapid filling of the left ventricle, C. Closure of the aortic valve, D. Contraction of the atria', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]