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
A patient presented with unilateral proptosis which was and increases on bending forward. No thrill or bruit was present. MRI shows a retroorbital mass with enhancement. The likely diagnosis is - 
Select and explain. 
A. AV malformations, B. Orbital encephalocoecle, C. Orbital varix, D. Neurofibromatosis
C: Orbital varix
Answer: C: Orbital varix 
Explanation: All are features of Orbital varix. Other circulatory disorders causing unilateral proptosis : angioneurotic edema, Orbital aneurysm. Ref: AK Khurana 6thE pg404 Img ref