Final answer:
Poe achieved the decision on the effect of the poem when he wrote this stanza, creating a sense of melancholy and despair.
Step-by-step explanation:
Poe achieved the decision on the effect of the poem when he wrote this stanza. The stanza sets up the climax of the poem, as the speaker implores the raven to answer if he will be reunited with his lost love, Lenore. The raven's response of 'Nevermore' adds a touch of horror and finality to the poem, creating the desired effect of melancholy and despair.