The poetic device that the poet uses to separate the ideas in the first two stanzas of this poem from the last two stanza's is D. The change from ballad form in the beginning to common form at the end.
Explanation:
Burns made this poem by deconstructing songs and ballads as an inspiration, that's the reason why the poem changes from the first stanzas to the lasts ones, not only in their foundation but also in the devices he used the first two stanzas have simile while the other two don't.
