This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Optics and Errors of Refraction, Subject name: Ophthalmology
The main corneal mechanism holding the LASIK flap in place after surgery is 
Select and explain. 
A. Endothelial pump, B. Stromal collagen adhesions, C. Bowman's layer-stromal adhesions, D. Endothelial-Descemet's membrane forces
A: Endothelial pump
Answer: A: Endothelial pump 
Explanation: In LASIK surgery after creating a corneal flap and ablating the midstromal tissue , the flap is reposited back without sutures. The main mechanism holding the flap is corneal endothelial pumps.