The best examples of alliteration from the provided lines in Edgar Allan Poe's "The Raven" are:
C: “while I nodded nearly napping suddenly there came a tapping as of someone gently rapping rapping at my chamber door.”
In this line, the repetition of the "n" sound in "nodded," "nearly," "napping," and "tapping," as well as the repetition of the "r" sound in "raping" and "rapping," creates a strong use of alliteration.
While other lines contain some alliteration, this line has the most pronounced and consistent repetition of initial consonant sounds.