This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NEET Jan 2020, Subject name: Social & Preventive Medicine
[{'content': 'Major source of cyanocobalamin vitamin is:- \nSelect and explain. \nA. Animal only diet, B. Plant only diet, C. Sunlight, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Vitamin B12 Synthesized exclusively by microbes. Dietary source is exclusively of animal origin Vitamin B12 deficiency clinical manifestations: Haematological: Megaloblastic anemia, Hypersegmentation of neutrophils. Neurological: Demyelination in peripheral nerves and spinal cord', 'role': 'assistant'}]