Why is Macduff able to kill Macbeth?

A. Because Macduff was born by cesarean section

B. Because Macduff uses witchcraft to defeat Macbeth

C. Because Macduff is avenging his wife and child

D. Because Macduff is more honorable than Macbeth

Macbeth tells Macduff that he was told by the witches that nobody will be able to kill him who is 'born of woman'. Macduff replies 'let the fates that told you this tell thee, Macduff was of his mother's womb untimely ripped.'

Therefore the answer is A., Because Macduff was born by cesarean section.