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
A patient with history of running nose and pain over medial aspect of the eye presents with sudden onset of high grade fever, prostration, chemosis, proptosis and diplopia on lateral gaze with congestion of the optic disc. Which of the following is the most likely diagnosis: 
Select and explain. 
A. Acute ethmoidal sinusitis, B. Orbital Cellulitis, C. Cavernous Sinus Thrombosis, D. Orbital Apex Sundrome
C: Cavernous Sinus Thrombosis
Answer: C: Cavernous Sinus Thrombosis 
Explanation: C i.e. Cavernous Sinus Thrombosis