Q. A 58-year-old woman comes to the clinic for a regular follow-up. She currently has no symptoms. The patient's medical history is significant for diabetes melilites and hypertension. She is not compliant with her medications. Vital signs show BP: 158/94, HR: 90 bpm, respiratory rate: 14/min, and oxygen saturation: 96%. Her cardiac pressure-volume loops are shown below. On cardiac auscultation, at which of the following points is the physician most likely to hear an abnormal heart sound?