A neurotransmitter is a signal which transmits information between neurons at the end of the axon. This neurotransmitter can either be excitatory or inhibitory. Whenever an action potential is triggered within a neuron, the neurotransmitter releases this action potential into the synapses at the axon as either an excitatory or inhibitory signal before a new action potential is triggered.
You know that there is a difference between plant cells and animals cells. The plant cells have a cytoplasm while the animal cells do not. Therefore the answer must be C.