This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
A 45-year-old woman has developed increasing SOB on exertion and fatigue. She has a loud systolic ejection murmur heard best at the left sternal border, and the murmur increases with standing. A double apical impulse is also felt.For the patient with a systolic murmur, select the most likely diagnosis. 
Select and explain. 
A. aortic stenosis, B. HOCM, C. mitral regurgitation (chronic), D. tricuspid regurgitation
B: HOCM
Answer: B: HOCM 
Explanation: HOCM often has a bisferiens pulse. It can also be found in pure aortic regurgitation or combined aortic regurgitation and aortic stenosis.