This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anatomy
[{'content': 'In which of the following cardiac structure is middle cardiac vein located? \nSelect and explain. \nA. Anterior AV groove, B. Posterior AV groove, C. Anterior interventricular sulcus, D. Posterior interventricular sulcus', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Posterior interventricular vein or middle cardiac vein runs in the posterior interventricular sulcus and may drain into the right atrium or into the coronary sinus.', 'role': 'assistant'}]