The correct answer is:
B. Structure.
Explanation:
Poems are literary works with specific chosen words to express and create an effect on the reader, a poem usually follows specific rules to create rhyme and tone, the way a poem is divided is part of its structure. A poem is divided by lines and stanzas to express feelings and ideas in a better way (this is known as form); stanzas are paragraphs separated by a blank line, each stanza is composed by lines that follow the same length, rhyme and message, in a poem every stanza usually has the same number of lines.