The correct answer is A. Alternating lines are about the same length and all end with a dash.
Explanation:
In most poems, lines follow a specific structure based on the number of syllables/words and other features such as rhyme or use of punctuation. In the case of the poem presented, there is a fixed structure because at the end of all the lines there is a dash (-) which might be used to replace a punctuation mark such as a comma and to create a pause between verses. Besides this, the length of verses 1 and 3 are similar, as well as the length between verses 2 and 4, which means alternating lines have a similar length based on the number of words and length of these. Thus, the option that best describes the structure is A.