B. Charle's because it is showing possession
The supernatural plays a large role in Macbeth. Had the witches not talked to Macbeth in the beginning of the play & told him of what he could become, none of the events that followed would have taken place. This gives an overall dark mood to the story. The mood relates to the play's central conflicts because after talking to some really dark and evil beings, Macbeth does some dark and evil things.
To give your characters struggles and/or motivation, you need to find something they want to strive toward. Your character is a person, just like anyone in real life. They have goals, they have things they hate. They have a backstory that could provide a reason for their struggles, such as they grew up in a fairly wealthy home, but now they got disowned and are dealing with how to make their own money.
Motivation tends to come from a struggle. For example, the character that is struggling with how to make their own money also has a motivation: money. They are used to having money, that now that they don't, they're going to try to get that money back. Sometimes, the character will have a lull in their motivation, which gives a perfect chance for a climax in the story. Something big happens to give them their push. Maybe they lose the apartment they were staying in because they were too lazy to find a job. Or maybe their significant other tells them that because they're such a worthless, jobless loser, that they're breaking up. No matter what this big event is, it shakes the character out of whatever lull they've been having and shows them that they need to be able to overcome their struggle, therefore providing them with their motivation back tenfold.
I hope this explains this well enough for you, but I can always try to answer in more detail if you'd like.
