An action potential in a neuronal membrane differs from a graded potential in that

A)an action potential requires the opening of Ca²⁺ channels,whereas a graded potential does not.
B)an action potential is propagated without decrement,whereas a graded potential decrements with distance.
C)an action potential has a threshold,whereas a graded potential is an all-or-none phenomenon.
D)movement of Na⁺ and K⁺ across cell membranes mediate action potentials,while graded potentials do not involve movement of Na⁺ and K⁺.
E)action potentials vary in size with the size of a stimulus,while graded potentials do not.