This contains neurotransmitters that allow a signal to cross from one neuron to another:
A. axon
B. endocrines
C. cell gap
D. synapse

D. synapse.

Explanation: Neurotransmitters are released into the space between the two neurons. This space is called the synapse. When neurons communicate, the neurotransmitters from one neuron are released, cross the synapse, and attach themselves to special molecules in the next neuron called receptors. Hope this helps ^-^.

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