Answer: The correct answer for the blank is B. Axon terminals
Axon terminals are the branches at the end of the axon. They play significant role in the transduction of signals. They release chemical substances called as neurotransmitters in the synapse ( space between the two neurons). These substances are packed into synaptic vesicles.
On the contrary, myelin sheath is the insulation around axon. Cell body is present prior to the axon and neural receptors are present on the postsynaptic neurons.
Thus, the branches at the end of the neuron are called as Axon terminals.