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: Medicine
A child presents with unilateral proptosis which is compressible and increases on bending forwards. It is non-pulsatile and has no thrill or bruit. MRI shows retroorbital mass with echogenic shadows. The most probable diagnosis is 
Select and explain. 
A. Orbital varix, B. Orbital encephalocoele, C. Orbital A-V malformation, D. Neurofibromatosis
A: Orbital varix
Answer: A: Orbital varix 
Explanation: None