Epithelial xerosis of the conjunctiva is caused by: (A) Trachoma, (B) Xerophthalmia, (C) Diphtheria, (D) Pemphigus
Answer is B. Epithelial xerosis:  It occurs due to hypovitaminosis -A. 
Epithelial xerosis may be seen in association with night blindness or as a part and parcel of the xerophthalmia (the term which is applied to all ocular manifestations of vitamin A deficiency which ranges from night blindness to keratomalacia