Which set of solutes is present at elevated concentrations inside cells rather than in plasma?

1. Plasma and interstitial fluid resemble each other far more than either resembles the fluid inside cells. 2. Both extracellular fluids carry high sodium, chloride and bicarbonate. 3. Intracellular fluid instead carries elevated potassium, phosphate, magnesium and protein. 4. Sodium therefore cannot belong to the intracellular list, which rules out the sodium options. 5. Sodium and potassium pumps in the membrane keep this difference in place using ATP. _Source: OpenStax Anatomy and Physiology (CC BY 4.0), Ch 26 "Fluid, Electrolyte, and Acid-Base Balance", section Composition of Body Fluids_