What role does potassium play in the human body?

Potassium plays a crucial role in maintaining water balance and facilitating nerve impulse transmission in the human body. It is an essential electrolyte that helps regulate fluid balance both inside and outside of cells, ensuring that they function optimally. Potassium is involved in various physiological processes, including muscle contraction and nerve signal conduction, by helping maintain the electrochemical gradient across cell membranes. This allows for the proper communication between nerve cells and muscle cells, which is vital for movement and coordination.

In addition to these functions, potassium is key in regulating blood pressure and supporting heart function, as it counteracts the effects of sodium. A diet rich in potassium can help prevent hypertension and support overall cardiovascular health. Therefore, its importance in maintaining water balance and its critical role in nerve impulse transmission underline why this option is the correct response.