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
All of the following conditions can give rise to pseudoproptosis, EXCEPT: 
Select and explain. 
A. High myopia, B. Buphthalmos, C. Sinus mucocele, D. Lid retraction
C: Sinus mucocele
Answer: C: Sinus mucocele 
Explanation: Pseudoproptosis refers to apparent proptosis in the absence of orbital disease. It can be due to high myopia, buphthalmos, or lid retraction. Sinus mucocele usually result in intermittent proptosis. Causes of pulsating proptosis are: Carotid-cavernous fistula Aerial orbital vascular malformation Transmission of cerebral pulsations due to a defect of the superior orbital roof, as in the sphenoid dysplasia of type 1 neurofibromatosis Proptosis that increases on bending the head forward or with Valsalva's maneuver is a sign of venous orbital vascular malformation (orbital varices) or meningocele. Ref: Sullivan J.H. (2011). Chapter 13. Orbit. In P. Riordan-Eva, E.T. Cunningham, Jr. (Eds), Vaughan & Asbury's General Ophthalmology, 18e.