Movement of Ions Through Channels Occurs as a Result of Gradients

Movement of ions through channels occurs as a result of gradients. If left alone, these gradients would eventually run down (ie reach equilibrium) . How do active transporters (pumps) like the Na⁺/K⁺ ATPase maintain the gradients?

A) They pump charges only across the membrane, maintaining the electrical gradient.
B) They pump neutral elements (atoms) only across the membrane, maintaining the concentration gradient.
C) They pump ions across the membrane maintaining both electrical and concentration gradients.
D) They pump water across the membrane maintaining osmotic and concentration gradients.