Which two factors most strongly influence Macbeth's descent into moral corruption?

A) Lady Macbeth's counsel

B) Banquo's advice

C) ambition

D) guilt

I would say that A) Lady Macbeth's counsel and C) ambition were two factors which most strongly influenced Macbeth's descent into moral corruption. If it weren't for these two, he would never become so morally disgusting, and die in the end.