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
Normal serum calcium level is: 
Select and explain. 
A. 4-6 mg/dl, B. 9-11 mg/dl, C. 19-21 mg/dl, D. 20-30 mg/dl
B: 9-11 mg/dl
Answer: B: 9-11 mg/dl 
Explanation: Normal Blood Calcium level-9 : 11 mg/dl
Total Calcium level in the body is 1.5 kg.