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
Paranasal sinuses communicate with the nose through its openings. Following group of ethmoidal sinuses drain into superior meatus: 
Select and explain. 
A. Anterior, B. Middle, C. Posterior, D. Middle + Posterior
C: Posterior
Answer: C: Posterior 
Explanation: The frontal sinus drains into the anterior pa of the hiatus semilunaris the infundibulum. The maxillary sinus also drains into the hiatus semilunaris, as do the anterior and middle ethmoidal sinuses. The posterior ethmoidal sinuses drain into the superior meatus. The sphenoid sinus drains into the space above the superior concha called the sphenoethmoidal recess.