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
Night blindness is due to: 
Select and explain. 
A. Vitamin A deficiency, B. Retinitis pigmentosa, C. High myopia, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: d all of the above refkhurana 3 rd/e p. 289