A Fellow Student Is Studying Graded Potentials and Decides That

Multiple Choice

A fellow student is studying graded potentials and decides that any time K⁺ is involved, the potential must be hyperpolarizing. Which of the following arguments could accurately explain that the ion alone doesn't determine this?

A) Ions move based on an electrochemical gradient. If the concentration of K⁺ outside the cell is greatly increased, then it would move in, depolarizing the cell.
B) When an ion crosses the membrane, it brings its charge with it. Because K⁺ is positively charged, it can only depolarize a cell (make it less negative.)
C) K⁺ basically doesn't move across the membrane unless it is actively transported, and potentials involve the movement of ions through channels.
D) Many types of ions (with their charges) are located inside and outside the cell. It is the concentrations of those other ions that determines whether a channel opening will lead to a depolarizing or hyperpolarizing potential.