<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 75-year-old man is brought to the emergency department 20 minutes after an episode of being unconscious. He was playing with his 3-year-old granddaughter when he suddenly fell down and was unresponsive for 1-minute. He responded normally after regaining consciousness. He has had episodes of mild chest pain and abdominal discomfort for the past 2 months, especially while working on his car. He has hypertension treated with hydrochlorothiazide. He appears alert. His temperature is 37.1C 98.8F, pulse is 89min and regular, and blood pressure is 11088 mm Hg. Examination shows a 36 late systolic murmur at the right sternal border that radiates to the carotids. There is no swelling or erythema of the lower extremities. Neurologic examination shows no focal findings. Which of the following is the most likely cause of this patients symptoms?? A: Rupture of the chordae tendineae, B: Fibrosis of the sinus node, C: Asymmetric septal hypertrophy, D: Calcification of the aortic valve, E: Embolus in the pulmonary artery,  <response>: This is a clinical vignette describing a 75-year-old man with a history of hypertension who presented with a brief episode of loss of consciousness. Key findings include a late systolic murmur at the right sternal border radiating to the carotids, no focal neurologic deficits, and no evidence of peripheral edema. The differential diagnosis includes cardiac causes such as valvular abnormalities, conduction system disturbances, hypertrophic cardiomyopathy, as well as non-cardiac causes like transient ischemic attacks. The late systolic murmur localized to the right sternal border suggests aortic stenosis as the likely etiology. Calcification and reduced mobility of the aortic valve is a common age-related finding that can progress to cause turbulent flow and murmurs. The transient loss of consciousness was likely due to reduced cerebral perfusion from the obstructed left ventricular outflow.Choices A and E are not supported by the clinical findings. Choice B could cause syncope but would not produce the described murmur. Choice D, calcification of the aortic valve, is the most likely diagnosis given this patients age and physical exam.D: Calcification of the aortic valve 