This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nutrition and health, Subject name: Social & Preventive Medicine
[{'content': 'The earliest clinical sign of vitamin A deficiency is - \nSelect and explain. \nA. Conjunctival xerosis, B. Corneal xerosis, C. Bitots spots, D. Keratomalacia', 'role': 'user'}, {'content': "Answer: A \nExplanation: Conjuctival xerosis is the early manifestation of vitamin A deficiency. REF. PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICAL 21ST EDITION. PAGE NO - 568", 'role': 'assistant'}]