Final answer:
Macbeth is driven to evil primarily by The witches' prophecies, which set in motion his quest for power and are the initial catalyst in his chain of immoral acts.
Step-by-step explanation:
The catalyst that drives Macbeth to do evil is B) The witches' prophecies. The three Weird Sisters set Macbeth on his path of destruction with their prophecy that he will become king. Their words ignite a desire within him for power. Lady Macbeth's ambition further propels him to murder King Duncan, but the initial impetus comes from the witches. Once Macbeth has a taste of power, his own ambition and desire to secure his position lead to further evil acts, including the murders of Banquo and others. The play Macbeth by William Shakespeare demonstrates how external influences such as the witches, coupled with internal motivations like Macbeth's ambition and Lady Macbeth's manipulations, can lead to a tragic downfall.