Neural transmission across a mammalian synaptic gap is accomplished by

A)the movement of sodium and potassium ions from the presynaptic neuron into the postsynaptic neuron.
B)impulses travelling as electrical currents across the gap.
C)impulses causing the release of a chemical signal and its diffusion across the gap.
D)impulses ricocheting back and forth across the gap.
E)the movement of calcium ions from the presynaptic into the postsynaptic neuron.