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: Unknown
The first sign of Vit A deficiency is : 
Select and explain. 
A. Conjunctiva xerosis, B. Corneal ulcer, C. Keratomalacia, D. Bitot’s spot
A: Conjunctiva xerosis
Answer: A: Conjunctiva xerosis 
Explanation: Modified classification WHO (Xerophthalmia) XN : Night blindness
XIA : Conjunctival xerosis XIB : Bitot’s spots
X2: Corneal xerosis
X3A : Corneal ulceration/keratomalacia less than 1/3rd corneal surface
X3B : Corneal ulceration/keratomalacia equal to or more than 1/3rd corneal surface XS : Corneal scar
XF : Xerophthalmia fundus.