The answer is "their". theirs doesn't make sense. You use "There" when you are are talking about going somewhere. (I am going there.) They're (they are) is a conjunction and that doesn't make sense in the sentence (They're going to the mall) Hope this helps
I believe the answer is D, it makes the most sense to me. But you have my apologies if it is incorrect.
D is the only one that seems to suggest that the dagger in only in Macbeth's head. "Or art though but A dagger of the mind", it questions if the knife is actually there or not.
Why does Douglas make an allusion to the sons of ham in the passage