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': 'Which of the following opens directly into right atrium? \nSelect and explain. \nA. Anterior cardiac vein, B. Oblique vein, C. Middle cardiac vein, D. Great cardiac vein', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Following opens into right atrium\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Superior vena cava\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Inferior vena cava\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Coronary sinus\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Venae cordis minimae\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Anterior cardiac vein\n-\xa0\xa0\xa0\xa0\xa0\xa0\xa0 Right marginal vein', 'role': 'assistant'}]