What is it called when there is a difference between what one expects to happen and what actually happens?

Read the lines from "there was a child went forth" and answer the question. and the apple-trees cover'd with blossoms, and the fruit afterward, and wood-berries, and the commonest weeds by the road; and the old drunkard staggering home from the out-house of the tavern, whence he had lately risen, and the school-mistress that pass'd on her way to the school, and the friendly boys that pass'd—and the quarrelsome boys, and the tidy and fresh-cheek'd girls—and the barefoot negro boy and girl, and all the changes of city and country, wherever he went. which poetic device is exemplified in this stanza? select all that apply. allegory anaphora imagery metaphor