Why does the speaker use repetition in the phrases "lamp-light gloated o’er” and "lamp-light gloating o’er” in the excerpt?

to show that the electric light is flickering on and off in the darkened room, which contributes to a frightful mood
to emphasize that the light is shining on the spot where lenore will never sit again, which contributes to a lonely mood
to show that the speaker is having trouble seeing even with the light of the lamp turned directly on the chair, which contributes to a mysterious mood
to emphasize that the light is next to the chair where the speaker is sitting, which contributes to a sad mood