Which neurotransmitter always has inhibitory effects

A)  GABA 
B)  glutamate 
C)  acetylcholine 
D)  norepinephrine

GABA

GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter in the nervous system, playing a critical role in reducing neuronal excitability and regulating muscle tone.

Glutamate

An amino acid that acts as a neurotransmitter in the central nervous system.

Acetylcholine

A neurotransmitter in the nervous system that plays complex roles in transmitting nerve impulses at synapses, including muscle stimulation, attention, arousal, and memory.