Which among the following statements is TRUE about presynaptic inhibition?

Presynaptic inhibition provides a mechanism for controlling the efficacy of transmission at individual synapses. It is mediated by axo axonal synapses. Binding of neurotransmitters to the receptors mediating presynaptic inhibition leads to a reduction in the amount of neurotransmitter secreted by the postsynaptic axon. This reduction is caused either by a decrease in the size of the action potential in the presynaptic terminal as a result of activation of K+ or Cl- channels or by reduced opening of Ca2+ channels in the presynaptic terminal, thereby decreasing the amount of transmitter release. Presynaptic inhibition thus provides a mechanism whereby the "gain" at a paicular synaptic input to a neuron can be reduced without reducing the efficacy of other synapses that impinge on that neuron. Ref: Waxman S.G. (2010). Chapter 3. Signaling in the Nervous System. In S.G. Waxman (Ed), Clinical Neuroanatomy, 26e.