A 68 year old female with a history of hypertension and diabetes presents with chest pains intermittently for 4 days and now significantly worse acute onset shortness of breath. Her temperature is 37.1, blood pressure 85/65, heart rate 110, respirations 24, and oxygen saturation 79% on room air. Physical examination reveals diffuse pulmonary rales, a II/VI holosystolic murmur at the cardiac apex radiating to the axilla, and elevated jugular venous pressure. A Swan-Ganz catheter is inserted and the pulmonary capillary wedge pressure tracing shows large V waves. Her ECG shows significant ST segment elevation. Which of the following coronary arteries is the most likely culprit?