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
In the human body, which of the following trace elements is next to iron: 
Select and explain. 
A. Ca2+, B. Zn2+, C. Cu2+, D. Selenium
B: Zn2+
Answer: B: Zn2+ 
Explanation: 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)