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
Thinnest pa of retina 
Select and explain. 
A. surrounding optic nerve head, B. Foveola, C. Fovea, D. Nasally to fovea
B: Foveola
Answer: B: Foveola 
Explanation: Foveola High Yield Facts Posterior Pole: Macula + Optic nerve head. Optic disc: 1.5 mm Macula: 5.5 mm (Temporal to optic disc) Fovea - Centralis : Central depressed pa of Macula, 1.5 mm Foveola - 0.35 mm. Thinnest pa of retina after ora serrata. Contains no ganglion cells, only cones.