Final answer:
The structural element in the poem is A) Rhyme scheme; a pattern identified by the end sounds of lines within a stanza.
Step-by-step explanation:
One structural element in the poem is A) Rhyme scheme. The rhyme scheme can be identified by the pattern of the end sounds of the lines within a stanza. For instance, if we label each unique rhyme with a letter, we might have patterns like ABAB or AABB. In the context of the poem provided, the rhyme scheme is described using a series of letters such as 'a b a b c d d ce fe f', indicating a complex pattern where lines with the same letter rhyme with each other. Elements such as alliteration and assonance are also sound-related techniques in poetry, which include the repetition of consonant sounds and vowel sounds, respectively, but these are not structural per se.