This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Surfaces and Grooves, Subject name: Anatomy
[{'content': 'WRONG about venous drainage of hea: \nSelect and explain. \nA. Coronary sinus is guarded by Thebesian valve, B. Middle cardiac vein lies in posterior atrioventricular groove, C. Great cardiac vein accompanies left anterior descending aery, D. Venae cordis minimi open into all four chambers', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Middle cardiac vein lies in posterior interventricular (not atrioventricular) groove.', 'role': 'assistant'}]