Final answer:
The quote "She thinks to dance with me on my wife's grave!" best reflects John Proctor's view of Abigail's lack of morality. Option number b is correct.
Step-by-step explanation:
The quote that best represents John Proctor's belief that Abigail Williams is lacking decent moral convictions is "She thinks to dance with me on my wife's grave!"
This line indicates that Proctor sees Abigail as grievously disrespecting the sanctity of his marriage and the memory of his deceased wife, implying a severe lack of morals on her part. It conveys his outrage at her actions and her disdain towards societal and moral expectations.