A 20-year-old man comes to the physician for routine examination. He is afebrile and has clear breath sounds throughout. Cardiac examination shows a mid to late diastolic murmur on auscultation, loudest at the cardiac apex. 
Which of the following is the most likely cause for this patient’s murmur?: (A) Acute pericarditis, (B) Congenital heart defect, (C) Infective endocarditis, (D) Rheumatic fever
Answer is D. None