This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: nutrition and digestion, Subject name: Biochemistry
Which of the following is not a trace element? 
Select and explain. 
A. Zinc, B. copper, C. Selenium, D. calcium
D: calcium
Answer: D: calcium 
Explanation: Definition of trace elements : Elements present at concentrations of mg/dl in body fluids and mg/kg in tissues are referrd to as trace elements . Calcium reference range in blood : 8.6 - 10.3 mg/dl. Teitz textbook of clinical biochemistry, chapter Vitamins and trace elements.