This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Ophthalmology
Earliest symptom of retinitis pigmentosa – 
Select and explain. 
A. Ring scotoma, B. Night blindness, C. Tubular vision, D. None
B: Night blindness
Answer: B: Night blindness 
Explanation: Night blindness (nyctalopia) is the earliest symptom.