The sodium-potassium pump is called an electrogenic pump because it

Contributes to the membrane potential.

Explanation:

Sodium-potassium pump: In cellular physiology, a protein which is identified in many cells that helping in to maintain the higher concentration of potassium ions inside than that is in the surrounding medium and maintain the lower concentration of sodium ions inside than that of the surrounding medium.

This unbalanced charge transfer contributes in the separation of charge across the cell membrane. Sodium-potassium pump is known for important contributor to action potential which is produce by nerve cells.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.