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
Not a bone of quadrilateral cailage: 
Select and explain. 
A. Ethmoid, B. Vomer, C. Sphenoid, D. Maxilla
C: Sphenoid
Answer: C: Sphenoid 
Explanation: Sphenoid