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: Ophthalmology
Parenchymatous xerosis of conjunctiva is caused by –a) Trachomab) Vitamin A deficiencyc) Vernal catarrhd) Phlyctenular keratoconjunctivitise) Alkali burns 
Select and explain. 
A. ae, B. b, C. ab, D. ad
A: ae
Answer: A: ae 
Explanation: Parenchymatous xerosis :- Trachoma, Diphtheria conjunctivitis, SJS, Pemphigus, Thermal/ chemical/ radiational burn, lagophthalmos due to symblepharon.
Epithelial xerosis:- Vitamin A deficiency (Xerophthalmia).