Correct Answer: C. Right coronary artery
ST-segment elevation in leads II, III, and aVF indicates an inferior wall myocardial infarction, which is most commonly caused by occlusion of the right coronary artery (RCA). The RCA supplies blood to the inferior wall of the left ventricle in approximately 80% of people. The pattern of ST elevation in these specific leads is characteristic of RCA occlusion.
Why your answer is incorrect:
The left anterior descending (LAD) artery supplies the anterior wall of the left ventricle and the anterior two-thirds of the interventricular septum. Occlusion of the LAD typically causes ST-segment elevation in the precordial leads (V1-V6) and/or leads I and aVL, indicating an anterior wall MI, not an inferior wall MI.
The left circumflex artery supplies the lateral wall of the left ventricle. Occlusion typically causes ST-segment elevation in leads I, aVL, and sometimes V5-V6, indicating a lateral wall MI, not an inferior wall MI.
Left main coronary artery occlusion is often fatal and would present with widespread ST-segment elevation in multiple leads (both anterior and lateral) due to the extensive myocardial territory at risk, not limited to the inferior leads.
The posterior descending artery is usually a branch of the right coronary artery (in right-dominant circulation). While its occlusion can contribute to an inferior MI, the pattern described is more consistent with proximal RCA occlusion.