<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 19-year-old man presents to the clinic with a complaint of increasing shortness of breath for the past 2 years. His shortness of breath is associated with mild chest pain and occasional syncopal attacks during strenuous activity. There is no history of significant illness in the past, however, one of his uncles had similar symptoms when he was his age and died while playing basketball a few years later. He denies alcohol use, tobacco consumption, and the use of recreational drugs. On examination, pulse rate is 76min and is regular and bounding; blood pressure is 13070 mm Hg. A triple apical impulse is observed on the precordium and a systolic ejection crescendo-decrescendo murmur is audible between the apex and the left sternal border along with a prominent fourth heart sound. The physician then asks the patient to take a deep breath, close his mouth, and pinch his nose and try to breathe out without allowing his cheeks to bulge out. In doing so, the intensity of the murmur increases. Which of the following hemodynamic changes would be observed first during this maneuver?? A: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow, B: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow, C: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow, D: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow, E: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow,  <response>: This is a clinical vignette describing a 19-year-old man with progressive shortness of breath, chest pain, syncope, and a family history concerning for hypertrophic cardiomyopathy. The physical exam findings of bounding pulse, systolic murmur, and quadruple rhythm are consistent with dynamic left ventricular outflow tract obstruction. The Valsalva maneuver increases left ventricular outflow tract gradient by reducing venous return and ventricular volume. This leads to increased contractility via the Frank-Starling mechanism, causing the murmur to increase in intensity. The first hemodynamic change during the Valsalva maneuver is a transient increase in mean arterial pressure due to increased systemic vascular resistance. Heart rate decreases due to increased parasympathetic activity. Baroreceptor activity increases to buffer the increase in blood pressure.E: Mean Arterial Pressure, Heart rate, Baroreceptor activity, Parasympathetic Outflow 