What is a writ directed to the proper officer, notifying a defendant of an action instituted against them?

The correct choice is a summons, which is a legal document issued by a court that notifies a defendant that an action or lawsuit has been initiated against them. The purpose of the summons is to inform the defendant of the legal proceedings and to compel them to respond or appear in court. This essential step ensures that the defendant is aware of the action so they can defend themselves appropriately.

In contrast, a warrant is a legal document that authorizes law enforcement to arrest an individual or conduct a search. A subpoena is a document that orders an individual to appear in court or produce evidence, usually in the context of a trial or legal inquiry. An affidavit is a written statement confirmed by oath or affirmation, used as evidence in court, but it does not serve the purpose of notifying a defendant about an action against them. Therefore, the role of a summons is quite specific and crucial in the context of initiating legal proceedings.