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
Which of the following is not a primary mandibular space 
Select and explain. 
A. Buccal, B. Sublingual, C. Submandibular, D. Pterygomandibular
D: Pterygomandibular
Answer: D: Pterygomandibular 
Explanation: None