Final answer:
Voltage-gated calcium channels are the most abundant in the axon terminal and are key in triggering the release of neurotransmitters, enabling neuronal communication.
Step-by-step explanation:
The most abundant type of voltage-gated channel within the axon terminal that is responsible for the release of neurotransmitter is B) voltage-gated calcium channels. These channels are crucial because they open in response to the depolarization of the membrane when an action potential reaches the axon terminal. The influx of Ca2+ through these channels triggers the synaptic vesicles to fuse with the presynaptic membrane, allowing the release of neurotransmitters into the synaptic cleft. This process is essential for the communication between neurons and the propagation of signals throughout the nervous system.