This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Body Fluids, Subject name: Physiology
Highest concentration in extracellular compartment is of which ion- 
Select and explain. 
A. Na+, B. K+, C. Cl-, D. Ca2+
A: Na+
Answer: A: Na+ 
Explanation: Ans. is 'a' i.e., Na+ ComponentExtracellular fluid (ECF) (meq/1)Intracellular fluid (ICF) (meq/l)Na+K+C1-HCO3-Mg+2Ca+2PO4-21425.5103281[?]22[?]5414150410580 0001 75Protein (organic anion)5 (2g%)40 (16g %)