This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thorax, Subject name: Surgery
[{'content': 'Which vein is preferable for coronary by pass grafting- \nSelect and explain. \nA. Saphenous vein, B. Short saphenous vein, C. Epigastric vessels, D. Radial artery', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Saphenous vein o Most common conduits used is greater saphenous vein. Ideal characteristics of a saphenous vein conduit are that it should be atleast having diameter of 3.5 mm and free from any varicosity or areas of structure,o If the saphenous vein is inadequate or unavailable^ short saphenous vein can be used,o Other conduits for CABG :* Internal mammary artery- (Left or right) - Preferred arterial conduits for LAD - Patency rate > 90% at 10 years* Radial artery * Gastroepiploic artery * Inferior epigastric arteries", 'role': 'assistant'}]