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: Biochemistry
which one is the trace element? 
Select and explain. 
A. Copper, B. sodium, C. calcium, D. Fats
A: Copper
Answer: A: Copper 
Explanation: i) Microminerals (Trace elements)- less than 100mg/day a) Copper b) Iodine c) Iron d) Mangnese e) Selenium f) Zinc