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': 'Ragi is richest source of - \nSelect and explain. \nA. Carbohydrates, B. Iron, C. Calcium, D. Proteins', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ragi contain 344mg of calcium per 100g of ragi. REF. PARK'S TEXTBOOK OF PREVENTIVE AND SOCIAL MEDICAL 21ST EDITION. PAGE NO - 628", 'role': 'assistant'}]