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: Ophthalmology
[{'content': 'A 19 years old young girl with previous history of repeated pain over medial canthus and chronic use of nasal decongestants, presented with abrupt onset of fever with chills and rigor, diplopia on lateral gaze, moderate proptosis and chemosis. On examination optic disc is congested. Most likely diagnosis is: \nSelect and explain. \nA. Cavernous sinus thrombosis, B. Orbital cellulitis, C. Acute ethmoidal sinusitis, D. Orbital apex syndrome', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Cavernous sinus thrombosis', 'role': 'assistant'}]