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
If posterior epistaxis cannot be controlled, which aery is ligated: 
Select and explain. 
A. Posterior ethmoidal aery, B. Maxillary aery, C. Sphenopalatine aery, D. External carotid aery
C: Sphenopalatine aery
Answer: C: Sphenopalatine aery 
Explanation: Ligation technique is reserved for intractable bleeding where the source cannot be located or controlled by other techniques. The hierarchy of aeries used for ligation is: Sphenopalatine aery Internal maxillary aery External carotid Aery Anterior/posterior ethmoidal aery Earlier the most common aery ligated was maxillary aery but now endonasal sphenopalatine aery ligation (ESPAL) is the ligation of choice