C, the word new should have been knew
I believe its:
B- TO PROVIDE DETAILS TO SUPPORT THE ESSAY'S MAIN IDEA
Then she tells him her plan: while Duncan sleeps, she will give his chamberlains wine to make them drunk, and then she and Macbeth can slip in and murder Duncan. They will smear the blood of Duncan on the sleeping chamberlains to cast the guilt upon them.
I think the answer could possibly be b from my understanding