This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, Subject name: Ophthalmology
Blood retinal barrier is formed by 
Select and explain. 
A. Muller cells, B. Amacrine cells, C. Horizontal cells, D. Outer Plexiform layer
D: Outer Plexiform layer
Answer: D: Outer Plexiform layer 
Explanation: Ans. (d) Outer Plexiform layerRef: Retina by Ryan 6/e, p. 657; Khuranas Anatomy 2/e, p. 151Blood retinal barrier at 2 levels* Inner - Non-fenestrated capillaries of the retinal vessels (superficial capillary network in NFL and deep capillary network between INL and OPL)* Outer - tight junctions of RPE