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
Unilateral proptosis with bilateral VIth nerve palsy, diagnosis is: 
Select and explain. 
A. Grave's disease, B. Retinoblastoma, C. Pseudotumour of orbit, D. Cavernous sinus thrombosis
D: Cavernous sinus thrombosis
Answer: D: Cavernous sinus thrombosis 
Explanation: D i.e. Cavernous sinus thrombosis