Final answer:
Graded potentials increase in size as the stimulus strength increases, while action potentials are all-or-nothing and do not change in size with varying stimulus strength.
Step-by-step explanation:
Graded potentials are local changes in the membrane potential that vary in size depending on the size of the stimulus that elicits them. A larger stimulus will result in a larger graded potential. Graded potentials can cause depolarization or hyperpolarization of the membrane, depending on the specific ion channels that are activated.
On the other hand, action potentials are all-or-nothing events that occur when a graded potential reaches the threshold for firing. The size of the stimulus does not directly affect the size of the action potential.
Based on this information, the correct answer is A) graded potential. Graded potentials increase in size as the stimulus strength increases, while action potentials are all-or-nothing and do not change in size with varying stimulus strength.