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
[{'content': 'Sphenoid sinusitis pain is referred most commonly to -a) Occiputb) Vertexc) Frontald) Temporal region \nSelect and explain. \nA. ab, B. a, C. ad, D. bc', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Acute sphenoditis: ‘Headache – usually localized to the occiput or vertex. Pain may also be referred to the mastoid region.’\n\nAlso Know', 'role': 'assistant'}]