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
Which of the following sinuses is the first one to develop 
Select and explain. 
A. Frontal, B. Maxillary, C. Sphenoid, D. Ethmoid
B: Maxillary
Answer: B: Maxillary 
Explanation: Maxillary sinus is first to develop. It appears as a shallow groove on the medial surface of maxilla during fourth month of intrauterine life, grows rapidly during six to seven years, and reaches full the eruption after all permanent teeth erupts.