Short Answer: The Third One
The first aside of Macbeth's only conveys that he has been told two truths. The witches convey just enough to entice him, and they know that soon too smaller things will come about and they take advantage of that knowledge. He has become the Thane of Glamis by the death (in battle) of the former owner of the title. (A Thane is a royal title in Scotland). Now, because Cawdor has betrayed Duncan, his title has been stripped from him. So these are the 2 truths that Macbeth speaks of.
The second quotation shows how confused Macbeth is. Shakespeare spends quite a bit of time in the tragedies thinking about good and evil. The subject confuses Macbeth. He doesn't know if present events are good or evil. So what he's saying here is they cannot be evil. If they were, why was he told two things that have come true. He is astonished the fate has made him the Thane of Cawdor.
The Third Quotation is actually the answer you want to pick. The language is enough to scare any sane person to death. The images floating around in his mind are so vivid that his hair is falling out just contemplating their meaning!!! His heart pounds against his ribs; he is terrified even thinking about it. Whenever I come across this quotation and another from Hamlet, I am reminded that killing a ruler (especially one to whom you have offered hospitality as in Macbeth), is not a trivial matter. Shakespeare was Catholic and he was well aware that the penalty for such a death is at the bottom of the very pits of hell. His language in three should convey that to you.
Passage four is further meaning put to quotation three. You could pick it as your answer. The problem is that it is a reflection of what the meaning of three is. I would pick three as your answer, because that is Macbeth's gut feeling, but don't be surprised if the right answer is four.
