the role of rhythm is toRhythm in a poem is the beat that the poem follows. Here is a good definition of poetry : literary music. Here is an example of rhythm,
Once upon a midnught dreary as I pondered weak and weary
This is an example of a metrical rhyme scheme that is rhythmical it is the beginning of "The Raven" by Edgar Allen Poe. In this poem poe builds on the rhyme scheme with iambic pentameter throughout the tale of this persistant bird that will not leave him be. so its A