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
Passavant’s ridge is located on which of the following: 
Select and explain. 
A. Posterior wall of oropharynx, B. Anterior wall of oropharynx, C. Posterior wall of nasopharynx, D. Anterior wall of nasopharynx
C: Posterior wall of nasopharynx
Answer: C: Posterior wall of nasopharynx 
Explanation: The upper fibres of palatopharyngeus form a spincter internal to superior constrictor. These fibres constitute passavant’s muscle, which on contraction raises passavent’s ridge on the posterior wall of nasopharynx.