<prompt> Xerophthalmia Grade X-3ACorneal xerosisBitot spotCorneal ulcer involving less than 13 of corneal surfaceCorneal ulcer involving more than 13 of corneal surface  <response>: Ans. is c i.e., Corneal ulcer involving less than 13 of corneal surface WHO classification of xerophthalmia XN Night blindness XIA Conjunctival xerosis XIB Bitots spots X2 Corneal xerosis X3A Corneal ulcerationkeratomalacia affecting less than one-third corneal surface X3B Corneal ulcerationkeratomalacia affecting more than one-third corneal surface XS Corneal scar due to xerophthalmia XF Xerophthalmic fundus 