This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of orbit, Lids and lacrimal apparatus, Subject name: Ophthalmology
[{'content': '19 year 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 & rigor, diplopia on lateral gaze,moderate proptosis & 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: It Stas initially as a unilateral condition which soon becomes bilateral due to intercavernous connection. It should be differentiated from orbital cellulitis and panophthalmitis. Ref: ak khurana 6th edition pg no412', 'role': 'assistant'}]