Final answer:
The action of the sodium-potassium pump involves actively transporting sodium ions out of the cell, which is answer D) in the multiple-choice question provided.
Step-by-step explanation:
An example of the action of the sodium-potassium pump transport includes the transport of sodium out of the cell. The sodium-potassium pump is an active transport mechanism in which sodium (Na+) ions are pumped from the inside to the outside of the cell while potassium (K+) ions are pumped into the cell. This process uses energy in the form of ATP and moves ions against their concentration gradients, maintaining necessary concentration differences across the cell membrane.
Specifically, the pump moves three sodium ions out of the cell for every two potassium ions it moves into the cell. The overall action of this pump is vital for many cellular functions, including maintaining the electrochemical gradient that is essential for nerve cell activity.