D is your answer. Dashes are used to separate parts of the sentence that don't quite belong there, or are useless information that you could get away with not including in the sentence. A good way to think about it is that generally anything you think could be surrounded by parenthesis could also be put in dashes.
Hello! The answer is personification. In this context, trouble is given human-like characteristics when the author states that "it rested its weary head on [their] shoulder". I hope this helps!
