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': 'Which of these is a poor source of Vitamin D? \nSelect and explain. \nA. Fish fat, B. Whole milk, C. Cod liver oil, D. Egg', 'role': 'user'}, {'content': "Answer: B \nExplanation: Food Vit D ug/ 100 g of food Butter 0.5-1.5 Egg 1 Whole milk 0.1 Fish fat 5-30 Cod liver oil 200-750 Halibut liver oil 500-10,000 Ref: Park's textbook of Preventive and Social Medicine, 21st edition, page-570", 'role': 'assistant'}]