How does the intracellular fluid compartment differ from the extracellular fluid compartment?

a) Sodium ions are more concentrated inside cells than in the plasma.
b) Bicarbonate ions (HCO₃⁻) are more concentrated inside cells than in either the interstitial fluid or plasma.
c) Proteins are more concentrated in the interstitial fluid than in cells.
d) Potassium ions are more concentrated inside cells than in the extracellular space.