What effect does the repetition of the phrase "in this kingdom by the sea" have in Poe's "Annabel Lee"?

A.
It lends the poem a fairy-tale atmosphere.

B.
It explains why Annabel Lee and the speaker are forbidden to love each other.

C.
It reminds readers that the speaker is just a child.

D.
It explains why Annabel Lee is buried in an ornate tomb.