<prompt>  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 patients murmur?Acute pericarditisCongenital heart defectInfective endocarditisRheumatic fever 