Answer: Subjuntivo
Necesitan que tú deshagas lo que hiciste.
They need you to undo what you did.
Step-by-step explanation: The subjunctive (deshagas) is found in the subordinate clause of sentences that contain a change of subject from the main clause to the subordinate clause. "Ellos necesitan" subject = "Ellos" ; "que tú deshagas" subject = "tú". (There is a change of subject.)
