Final answer:
Judge Zellar performed an in camera inspection, where he privately reviewed documents to decide on their disclosure to the plaintiff. The correct option is 1) an in camera inspection.
Step-by-step explanation:
Judge Zellar made an in camera inspection when he decided if a plaintiff could see the interrogatories procured by the defendant. An in camera inspection refers to a judicial review of documents in private, where the judge examines the contents alone to determine relevancy or privilege before they are made available to the other party. This method prevents unnecessary disclosure of confidential information unless it's deemed essential for the case.