You are answering a USMLE-style medical question. Question: A previously healthy 46-year-old woman comes to the physician because of progressive shortness of breath, fatigue, and chest pain during exercise for the last 6 months. She does not smoke. Her maternal uncle had similar symptoms. Cardiac examination shows wide splitting of S2. The second component of S2 is loud and best heard at the 2nd left intercostal space. The lungs are clear to auscultation. Which of the following is the most likely cause of this patient's cardiac findings? Options: A) Increased right ventricular preload B) Increased left ventricular preload C) Increased right ventricular afterload D) Increased left-to-right shunting Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.