Final answer:
Lorcaserin acts as a serotonin agonist.
Step-by-step explanation:
Out of the given options, lorcaserin acts as a serotonin agonist. Serotonin agonists are drugs that bind to and activate serotonin receptors, mimicking the effects of serotonin in the body. Lorcaserin is a medication used for weight management and works by activating serotonin receptors in the brain to reduce appetite.