The ironic action that Danforth takes when speaking with Elizabeth Proctor in Act 4 of "The Crucible" is:
A. He asks her to help get Proctor to confess.
This is ironic because Danforth, who is a figure of authority in the witch trials and represents the law, is essentially asking Elizabeth to manipulate her husband into confessing to something he did not do, which highlights the absurdity and tragedy of the situation they are all in. His request underscores the moral corruption of the court and the desperation of the circumstances.