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
All open into middle meatus except ? 
Select and explain. 
A. Frontal sinus, B. Sphenoid sinus, C. Maxillary sinus, D. Ethmoidal sinus
B: Sphenoid sinus
Answer: B: Sphenoid sinus 
Explanation: Ans. is 'b' i.e., Sphenoid sinus Pa of lateral nasal wallOpeningsInferiorNasolacrimal ductMiddleFrontal sinus, Maxillary sinus, Anterior ethmoidal sinusSuperiorPosterior ethmoidal sinusSphenoethmoidal recessSphenoid sinus