[Soul]

This woman has a history of rheumatic fever during her childhood. generally mitral valve is the first valve to be affected in RHD. Initially it presents with MR but gradually scarring of the valve causes MS. I guess the correct answer in this case should be- B "fish mouth" shape due to chronic rheumatic scarring.
Though 3D echocardiography can view 'fish mouth' appearance it's generally unavailable in many centres. Arjun is right. Then the answer is A-Billowing of valve leaflet during systole into left atrium-Mitral valve prolapse.. Therefore, physical examination is very important. Mid systolic click with late systolic murmur in MVP whereas Mid diastolic murmur with OS in MS will certainly help.
If 3D echo was not done then the answer is A. (i am not sure whether 2D echo can identify 'fish mouth' apperance of MV, though stenosis as small as 0.4 cm2 can be identified by 2D echo).
We may use the famous Sherlock Holmes technique: "It is an old maxim of mine that when you have excluded the impossibility, whatever remains, however improbable, must be the truth."
If the answer is B- then the mitral stenosis should be very severe and there should be signs and symptoms like dyspnea, chest discomfort etc etc... But this woman is not complaining of any.
Vegetations are usually in Infective endocarditis --as a complication of rheumatic heart disease. But fever is must in this case and there are no other s/s of IE.
So most likely Dx is "A". As a said before physicals are important. Listen heart murmur and make a Dx.