A 72 year old female with no significant past medical history passes out while exercising. He has intermittent exertional chest pains and dyspnea on exertion as well. Her physical examination reveals a III/VI late-peaking creshendo-decreshendo murmur at the right upper sternal border and a III/VI holosystolic murmur at the apex. Her S2 heart sound is very soft and her carotid upstroke is weak and delayed. Which of the following is most likely causing her symptoms?

B) Aortic valve stenosis

C) Mitral valve regurgitation

D) Mitral valve stenosis

E) Mitral valve prolapse