Anxiolytics modify the transmission of an inhibitory neurotransmitter.'

GABA (gamma-Aminobutyric acid)

Explanation:

Gamma-Aminobutyric acid or GABA is an inhibitory neurotransmitter present in the mammalian central nervous system. Since this is inhibitory in action therefore it reduces the excitability in the nervous system. The low level of GABA could cause mood disorders and anxiety.

Anxiolytics or anti-anxiety drugs which are taken to overcome the symptoms of the anxiety disorders. The anxiolytics act on the GABA molecules by modifying the subunits of GABA which increases its affinity for the GABA receptors. It causes potentiation of the GABA.

Thus, GABA is the correct answer.

Anti-anxiety agents are drugs used to alleviate the symptoms of anxiety and associated disorders