Which two factors influence macbeth's decision to kill king duncan?

The witches prophecy is what influences him to kill King Duncan, because they predicted that he will become king. 

The best answer in my opinion would be the last one. i hope this

A. they give the reader hope. if the whole book was dark & unhopeful it’d be a little less interesting, little moments make it more interesting to read because then you want to know what happens. if it’s all dark there’s no point in reading if you already know the outcome of it.