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
Paralysis of 3rd, 4th, 6th nerves with involvement of Ophthalmic division of 5th nerve, localizes the lesion to- 
Select and explain. 
A. Cavernous sinus, B. Apex of orbit, C. Brainstem, D. Base of skull
A: Cavernous sinus
Answer: A: Cavernous sinus 
Explanation: *Paralysis of 3rd, 4th, 6th nerve and involvement of Ophthalmic division of 5th nerve -> cavernous sinus thrombosis. *Paralysis of 3rd, 4th, 6th nerve, Ophthalmic division of 5th nerve plus optic nerve signs -> orbital apex syndrome. Ref: Khurana 7th/e p.428