The best answer to the question about the irony behind Danforth’s reasoning for refusing to pardon the remaining prisoners or postpone their hangings in Act 4 of "The Crucible" is:
**b. It is ironic that his idea of justice extends more to those who have already been hanged than to those who are still alive.**
This highlights Danforth's warped sense of justice, as he prioritizes the integrity of the court and the previous executions over the lives of the remaining prisoners, demonstrating a profound irony in his reasoning.