Answer:
b. excessive ambition for her husband.
Step-by-step explanation:
The character flaw that most seems to motivate Lady Macbeth to plan Duncan’s murder in Act I of "The Tragedy of Macbeth" is an excessive ambition for her husband. Lady Macbeth starts to plan Duncan's death when she hears the witches' predictions. It is not out of her excessive love of money that she acts or of fear of losing her husband in battle. Macbeth is coming home victorious after the battle. Lady Macbeth does not feel insecure that her husband loves her. She acts out of pure and excessive ambition for her husband to become king.