Personally I don't like any of these answer choices. However, this one makes the most sense in this context. The others would need a much different set-up earlier on in the passage. "Incidentally" does not require such a set up, which is why it is the only one that fits.
I think that it is Brutus's guilty soul and that it has taken over his dreams. I think this because<span>it say Brutus's evil spirit which lead me to beileve guilty soul.</span>
