The correct answer is A. Lady Macbeth will make sure the guards are drugged, allowing Macbeth to sneak in and stab the king to death.
The plan is to drug the guards first, because they are guarding King Duncan. Once they are sleeping, Lady Macbeth will take out their daggers, Macbeth will find the daggers, go into Duncan's room, and then stab him. Later on, he will become the next king, and Lady Macbeth goes crazy (obviously, not part of the plan).
"what" and "who" are interrogative pronouns. a quick memory aid for that: consider detectives, conducting interrogations. they ask questions, such as "what happened?" or "who did it?"
Modocs never killed grizzly bears because, in the book he stated that, grizzly bears help the enviroment and the keep the circle of life stable.
He is trying to narrow a general topic by listing subtopics.