The correct option is 3: K+ Potassium ion (K+) is, without question, the most abundant and vital cation found within the cytosol of virtually all living cells. The fundamental distinction between the inner (intracellular) and outer (extracellular) environment of a cell is their ion composition, and K+ defines the interior. The intracellular concentration of K+ is maintained at a remarkably high level, typically ranging from 120 to 150 millimoles per…Read More