This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vitamins and Nutritional Deficiencies, Subject name: Social & Preventive Medicine
Xerophthalmia is considered a problem in a community if:- 
Select and explain. 
A. Night blindness >1%, B. Bitot spots >1%, C. Corneal ulceration > 0.05%, D. Corneal ulcer >0.5%
A: Night blindness >1%
Answer: A: Night blindness >1% 
Explanation: Prevalence criteria for determining the Xerophthalmia problem in a community: Criteria Prevalence Night blindness >1.0% Bitot's spots >0.5% Corneal xerosis / corneal ulceration / keratomalacia >0.01% Corneal ulcer >0.05% Serum retinol >5.0%