Final answer:
The axon terminal is the structure at the end of a neuron that sends signals to other neurons, and the correct answer to the question is A. Axon terminal.
Step-by-step explanation:
The structures located at the end of a neuron responsible for sending the signal to other neurons are known as axon terminals. Also referred to as end buttons, terminal branches of axon, and synaptic knobs, these specialized endings are the points at which neurons make synaptic connections with other neurons or target cells. At the axon terminal, neurotransmitters are released into the synapse, the gap between neurons, and bind to receptors on the postsynaptic cell to continue the signal transmission process.
The correct answer to the question is A. Axon terminal.