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
Orbital cellulitis is a complication of -a) Parasinusitisb) Faciomaxillary traumac) Endoscopic sinus surgeryd) All of these 
Select and explain. 
A. ac, B. a, C. ab, D. bc
C: ab
Answer: C: ab 
Explanation: None