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: Surgery
[{'content': 'Plunging ranula is a type of \nSelect and explain. \nA. Retention cyst, B. Extravasation cyst, C. Implantation cyst, D. Malignant tumor', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]