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: ENT
Choana is - 
Select and explain. 
A. Anterior nares, B. Posterior nares, C. Tonsils, D. Larynx
B: Posterior nares
Answer: B: Posterior nares 
Explanation: Internal nose is divided into right and left nasal cavities by nasal septum.
Each nasal cavity communicates with the exterior through nares or nostrils and with nasopharynx through posterior nasal aperture or posterior nares or choana.