This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S., Subject name: Medicine
[{'content': 'Complete occlusion of coronary artery is denoted by which score in TIMI by angiography? \nSelect and explain. \nA. 0, B. 1, C. 2, D. 3', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A. 0Coronary AngiographyWhen assessed angiographically, flow in the culprit coronary artery is described by a simple qualitative scale called the thrombolysis in myocardial infarction (TIMI) grading system:a. Grade 0 indicates complete occlusion of the infarct-related arteryb. Grade 1 indicates some penetration of the contrast material beyond the point of obstruction but without perfusion of the distal coronary bedc. Grade 2 indicates perfusion of the entire infarct vessel into the distal bed but with flow that is delayed compared with that of a normal arteryd. Grade 3 indicates full perfusion of the infarct vessel with normal flow.', 'role': 'assistant'}]