This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diagnostic and operative ENT, Subject name: ENT
Caldwell luc approach opens 
Select and explain. 
A. Maxillary sinus, B. Frontal sinus, C. Sphenoid sinus, D. Ethmoid sinus
A: Maxillary sinus
Answer: A: Maxillary sinus 
Explanation: Caldwell luc approach opens maxillary sinus. Ref- Dhingra, 6th edition, Page 412.