Practice question

Go with B — High density of voltage-gated Na+ channels. Within Action potential, that statement lines up with the standard definition and the usual exam wording you’ll see. In plain terms, excitable-cell physiology turns on membranes, ions, and signalling steps, and High density of voltage-gated Na+ channels captures the correct piece of that story. Holding that picture in mind makes High density of voltage-gated Na+ channels feel natural rather than something you only memorise. Link the term to a real body example (organ, tissue, or ion flow) so the idea stays concrete under exam pressure. A short mental diagram helps — start from stimulus or structure, follow the pathway, and stop at the functional result described by High density of voltage-gated Na+ channels.