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
Submandibular duct is exposed via intraoral approach by incising the: 
Select and explain. 
A. Buccinator, B. Mucous membrane, C. Masseter, D. All of the above
B: Mucous membrane
Answer: B: Mucous membrane 
Explanation: None