Person who brings an action at law

The correct answer is A. Plaintiff.

A plaintiff is the party who brings a civil lawsuit against another party, the defendant. The plaintiff alleges that the defendant has caused them harm, and seeks damages or other relief from the court.

A litigant is a person who is involved in a lawsuit, either as a plaintiff or a defendant.

A deponent is a person who gives testimony under oath in a deposition, which is a pre-trial proceeding in which the parties question witnesses.

A defendant is the party who is sued in a civil lawsuit. The defendant