Answer:
B. This murderous shaft that's shot/Hath not yet lighted, and our safest way/is to avoid the aim.
Step-by-step explanation:
In this passage from Act II, Scene III, of "The Tragedy of Macbeth" by William Shakespeare, the lines that support the answer to the question of why Malcolm and Donalbain feel they need to leave Scotland is stated above. Malcolm and Donalbain think that the man who killed their father might be aiming at them. They think it is not safe for them to remain in Scotland because they have to avoid the aim.