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: Pathology
[{'content': 'All the following affects absorption of calcium, EXCEPT \nSelect and explain. \nA. Citric acid, B. Retinoic acid, C. Phytates, D. Oxalates', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]