Read this stanza from "the raven."

back into the chamber turning, all my soul within me burning,
soon again i heard a tapping something louder than before.
"surely," said i, "surely that is something at my window lattice;
let me see, then, what thereat is and this mystery explore–
let my heart be still a moment and this mystery explore; –
'tis the wind and nothing more."

this stanza contributes to the suspense of the poem because

a) the reader knows what is making the noise while the speaker does not.
b) the speaker and the reader wait again to find out what is making the noise.
c) the tapping gets louder, which foreshadows that the noise is made by a bird.
d) the wind gets stronger and makes more noise against the speaker’s window.