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: Surgery
In halo sign seen in csf rhinorrhea: 
Select and explain. 
A. Blood is encircled with csf., B. CSF is encircled with blood., C. Both are mixed no demarcation., D. None of the above.
A: Blood is encircled with csf.
Answer: A: Blood is encircled with csf. 
Explanation: CSF rhinorrhea seen in
Lefort 2&3
Naso orbital ethmoid fracture.
Cribiform plate fracture.
Frontal sinus fracture.
Sphenoidal sinus fracture