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': 'Beri-Beri is caused by - \nSelect and explain. \nA. Thiamine, B. Folic acid, C. Riboflavin, D. Niacin', 'role': 'user'}, {'content': "Answer: A \nExplanation: - beri beri is due to the deficiency of thiamine. - it has 3 main forms. Dry form characterised by nerve involvement. Wet firm characterised by hea involvement and infantile beri beri. Reference : Park's textbook of preventive and social medicine, 23rd edition, pg no:618 <\\p>", 'role': 'assistant'}]