The definition that most closely reflects the poem is C. Villanelle
How to explain
The poem closely aligns with the structure and characteristics of a villanelle. It spans 19 lines with a repeated rhyme scheme "aba aba aba aba aba abaa."
It maintains the repeating lines from the first stanza throughout the poem, alternating their positions in subsequent stanzas. The final stanza utilizes these repeated lines as a rhymed couplet.
This structure, along with the thematic repetition of the message about heroism and inner battles, mirrors the distinct features of a villanelle.