Task: Question Answering
Input (English): Question: Alcohol is included in the group of sedative or depressant drugs because it acts as: 
 Options:  <1> Cholinergic receptor agonist: nicotinic and muscarinic. <2> Antagonist of serotonergic (5 HT) and cholinergic receptors. <3> Noradrenergic receptor agonist and serotonin antagonist. <4> Antagonist of NMDA receptors and agonist of AMPA receptors. <5> GABA-a receptor agonist and NMDA receptor antagonist.
Output (English): 5