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: Physiology
[{'content': 'Which of the following organ is not involved in calcium metabolism: \nSelect and explain. \nA. Lung, B. Liver, C. Spleen, D. Skin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: C i.e. Spleen', 'role': 'assistant'}]