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
[{'content': 'Which of the following is not a trace element? \nSelect and explain. \nA. Zinc, B. copper, C. Selenium, D. calcium', 'role': 'user'}, {'content': 'Answer: D \nExplanation: 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.', 'role': 'assistant'}]