A teenager has seen her local physician complaining of persistent and severe headaches. Her physician diagnosed migraine and prescribes sumatriptan, which acts by which of the following mechanisms?

Sumatriptan is a serotonin 1D agonist that is used to abo migraine headaches. It is also effective in the treatment of cluster headaches. Currently, no dopamine 1 (D1) agonists, GABAB antagonists, or muscarinic m3 (M3) antagonists are used clinically.