Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter in the mammalian central nervous system. When GABA binds to specific receptors on the postsynaptic membrane, it causes ligand-gated potassium channels to open. This results in the rapid efflux (diffusion out) of positively charged potassium ions (K+\text{K}^+K+) from the postsynaptic neurone.
Explain how the efflux of K+\text{K}^+K+ ions inhibits the postsynaptic neurone from generating an action potential.