Answer:
D. They foreshadow events.
Step-by-step explanation:
The three witches in the play Macbeth are considered the embodiment of various abstract elements, such as evil, fate and temptation. Their most important role is to foreshadow the events that will occur in the play. Foreshadowing occurs when the author gives the readers a hint of what is going to happen later in the story. It is unclear whether the witches are indeed only messengers, or whether they have some ulterior motive for manipulating the characters in the story.