21. In a resting animal cell, what is the typical state of the K⁺ leak channels? (A) Closed and unresponsive to external stimuli (B) Open, allowing K⁺ to move down its concentration gradient (C) Active, transporting K⁺ into the cell (D) Open, transporting K⁺ against its concentration gradient (E) Inactivated, preventing K⁺ movement