This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'In the human body, which of the following trace elements is next to iron: \nSelect and explain. \nA. Ca2+, B. Zn2+, C. Cu2+, D. Selenium', 'role': 'user'}, {'content': 'Answer: B \nExplanation: After Iron (18mg/day), zinc (11mg/day) comes next in total requirement among trace elements.Followed by manganese and copper.** NA, K, Ca, Cl, Ph, Mg are not trace elements.(ref: OP Ghai 8/e p123)', 'role': 'assistant'}]