A]
Read the sentence beginning "What need we fear ...." She is saying the exact opposite of A.
B]
Lady MacBeth is not contemplating suicide. The only way you could defend that is by realizing that everyone in Shakespeare's time was Catholic. Suicide is a mortal sin, so here Lady M. can already envision Hell. It is not because of suicide. It is because of guilt.
C]
She's not unhappy about her marriage. That is a 21st century reason for doing many things to get out of what is bad. It was not hers. She's trying to rub the blood from her hands, not throw her ring in the moat.
D]
I'm not sure about this, but I think she learned that early almost as soon as it happened.
This is one of those cases where nothing is right. In the first place she is sleep walking and having visions. It is why most people think she is going mad.
In the second, her primary problem is madness.
You cannot ever choose A, or C. They just don't fit the play and they are either contradicted or inferred to be wrong.
You can't choose B either. She is not thinking of suicide. Her motive is guilt. Though very obscure, you likely ought to choose D, but it is not correct. The trouble is that you should be given a question where the answer is in the speech itself, no matter how subtle.
There just isn't one here.
