This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Microbiology
The first sign of Vitamin A deficiency is 
Select and explain. 
A. Conjunctival xerosis, B. Corneal ulcer, C. Keratomalacia, D. Bitot's spot
A: Conjunctival xerosis
Answer: A: Conjunctival xerosis 
Explanation: Modified classification WHO (Xerophthalmia) XN: Night blindnessXIA: Conjunctival xerosis XIB: Bitot's spotsX2: Corneal xerosisX3A: Corneal ulceration/keratomalacia less than 1/3rd corneal surfaceX3B: Corneal ulceration/keratomalacia equal to or more than 1/3rd corneal surface XS: Corneal scarXF: Xerophthalmia fundus.