Final answer:
Action potential propagation rate is influenced by axon diameter and myelination (option A and C), but not by stimulus strength. The fastest propagation is through a thick, myelinated axon due to saltatory conduction and lower resistance in a larger space.
Step-by-step explanation:
Action potential propagation rate is influenced by several factors, but stimulus strength is not one of them. Instead, factors such as axon diameter and myelination play crucial roles.
For example, a thick, myelinated axon will propagate an action potential fastest due to two main mechanisms:
- Myelinated axons feature saltatory conduction, where the action potential 'jumps' from one node of Ranvier to the next, greatly increasing conduction speed.
- A larger axon diameter allows for less resistance within the axonal space, facilitating faster ion diffusion and signal propagation.
In contrast, continuous conduction in an unmyelinated axon results in a slower propagation of the action potential due to the necessity of voltage-gated Na+ channels being activated along the entire length of the axon.