This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy, Development and clinical examination, Subject name: Ophthalmology
Size of optic disc is 
Select and explain. 
A. 0.5mm, B. 1mm, C. 1.5mm, D. 2mm
C: 1.5mm
Answer: C: 1.5mm 
Explanation: Optic disc.The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye. Because there are no rods or cones overlying the optic disc, it corresponds to a small blind spot in each eye. The ganglion cell axons form the optic nerve after they leave the eye. It is a pink coloured, well defined veically oval area with average dimension of 1.76 mm horizontally and 1.88 mm veically. It is placed 3.4 mm nasal to the fovea. Reference: A.K.Khurana; 6th edition; Page no:263