A Potassium Channel Conducts K⁺ Ions Several Orders of Magnitude

A potassium channel conducts K⁺ ions several orders of magnitude better than Na⁺ ions, because …

A) the Na⁺ ion is too large to pass through the channel pore.
B) the hydrated Na⁺ ion occupies a larger volume compared to the hydrated K⁺ ion, and is too large to pass through the channel pore.
C) the Na⁺ ion is too small to interact with the channel in a way that facilitates the loss of water from the ion.
D) the Na⁺ ion cannot bind to the high-affinity K⁺-binding sites in the channel pore.