This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
Least common ion in EOF is 
Select and explain. 
A. Na, B. K+, C. CI, D. HCO3
B: K+
Answer: B: K+ 
Explanation: Predominent ions in ECF are Na+ and Cl-predominent ions in ICF are K+ ,Mg+,phosphate Table1.3.3 of Textbook of physiology AK Jain 4th edition page no.27.