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
After a radiograph revealed a sialolith (stone) in a patient's right submandibular duct, the surgeon exposed the duct an intraoral approach. In this approach, what tissues or structures must be cut through? 
Select and explain. 
A. Mucous membrane only, B. Mucous membrane and genioglossus muscle, C. Mucous membrane and mylohyoid muscle, D. Mucous membrane and hyoglossus muscle
A: Mucous membrane only
Answer: A: Mucous membrane only 
Explanation: The submandibular duct is found deep to the mucous membrane of the mouth, but superficial to the muscles of the tongue and the muscles on the floor of the mouth. So, genioglossus, mylohyoid, and hyoglossus are deep to the submandibular duct.