52. Presynaptic facilitation occurs when: A) a neuron produces neurotransmitter at a more rapid rate than normal B) a neurotransmitter released by the postsynaptic neuron diffuses back across the synaptic cleft to the presynaptic neuron C) several presynaptic end bulbs release neurotransmitter simultaneously D) a second presynaptic neuron is stimulated to release more neurotransmitter by the action of neurotransmitter from a first presynaptic neuron E) one presynaptic neuron inhibits the release of neurotransmitter from a second presynaptic neuron.