What is a defendant's written reply to a plaintiff's petition called?

The term for a defendant's written reply to a plaintiff's petition is called an "Answer." In civil litigation, the defendant must respond to the allegations made by the plaintiff in the petition. The Answer typically addresses each allegation, admitting or denying them and can provide any defenses the defendant may have. This legal document is crucial for establishing the issues that will be contested during the trial.

The other options refer to different concepts in civil procedure. A "Response" might indicate another type of reply but isn't the specific term used for a defendant’s reply to a plaintiff. A "Counterclaim" involves the defendant asserting their own claim against the plaintiff within the same proceedings, thus serving a different purpose than merely responding. A "Motion" is a formal request made to the court for a specific ruling or order, not a direct reply to the plaintiff’s assertions. Therefore, "Answer" is the correct and precise term that encapsulates the defendant's official response to the allegations in the plaintiff's petition.