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
Plunging ranula is a type of 
Select and explain. 
A. Retention cyst, B. Extravasation cyst, C. Implantation cyst, D. Malignant tumor
A: Retention cyst
Answer: A: Retention cyst 
Explanation: None