Which theme is supported by Macbeth’s lines?

We still have judgment here; that we but teach
Bloody instructions, which being taught, return
To plague the inventor: this even-handed justice
Commends the ingredients of our poison'd chalice
To our own lips.

A. Darkness is dangerous.
B. Ambition unchecked can lead to corruption. ANSWER: B
C. Things are not always what they seem.
D. Those without convictions are easily manipulated.