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: 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. Kerato malacia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]