C

Reasoning: Surgical control of refractory epistaxis commonly involves ligation of branches of the external carotid system such as the maxillary (sphenopalatine) artery, the anterior ethmoidal artery, or even the external carotid artery itself; the internal carotid artery is not ligated for nasal bleeding because of its critical cerebral supply and high morbidity risk [Cooke, 1985, PMID 4020270; Waldron, 1992, PMID 1527828].