I believe that the answer is D. In Act 1, Scene 7, Lines 39-49, Lady Macbeth asks why Macbeth has decided to cancel the assassination. She questions his strength of character by telling him he will "live a coward in thine own esteem," meaning that if he does not do it, he will be a coward. Later on, in the same act and scene, lines 56-58, she begins to doubt his manhood, stating that he will be less of a man if he were to back out now and not kill Duncan. This is why I believe the answer to your question is D.
B is the correct answer; past perfect continuous (progressive)
