Answer: D. structure
The building blocks/structure of every poem determines how the reader perceives it and this perception is greatly influenced by the poem’s rhyme scheme.
Rhyme schemes are simply patterns of rhyme concluding every line or stanza of a poem. They affect the rhythm of the poem as they can vary in each line or stanza. The commonest ones are ABAB (alternate rhyme), ABCB (simple four-line rhyme), ABBA (enclosed rhyme), AABBA (limerick), AABB (coupled rhyme), AAAA (monorhyme), and ABA BCB CDC (chain rhyme or terza rima). As you guessed, lines having identical alphabets rhyme with one another
Poets adopt rhyme schemes because they cause language to sound more pleasant and musing and they also help readers in memorizing.