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
[{'content': 'Predominant cation of intracellular fluid \nSelect and explain. \nA. Na+, B. K+, C. Ca+2, D. H+', 'role': 'user'}, {'content': 'Answer: B \nExplanation: K+ concentration in I.C.F is 155 mEq/L of H2O.(Ref: Textbook of physiology AK Jain 5th edition page no.26 table 1.3.3)', 'role': 'assistant'}]