What do neurotransmitters do? A. Cause the pre-synaptic neuron to open voltage-gated gates. B. Diffuse across the synaptic cleft and bind to specific receptor sites on the post-synaptic cell. C. Cause calcium to diffuse across the synaptic cleft and bind to specific receptor sites on the post-synaptic cell. D. Diffuse synaptic vesicles which releases molecules into the synaptic cleft.