Q. A 56-year-old homeless woman is brought to the emergency department by a local shelter volunteer when she is found feverish. The patient's medical history is unknown. The patient is conscious however appears malnourished. Vital signs show her blood pressure is 99/70 mm Hg, heart rate 102/min, respiratory rate 19/min, temperature 38.6 degrees Celsius. Multiple needle tracks are seen on the patient's forearms. Point-of-care echocardiography confirms the presence of a vegetation. Regarding the above vegetation, the affected valve is most commonly heard at which of the following locations?