Questions: Jackie negligently causes serious physical and economic harm to Roberto in a car crash. In the negligence action, Jackie would be referred to as the tortfeasor.

The answer is: tortfeasor.

Explanation:

• Tortfeasor: This is the correct term. A tortfeasor is a person who commits a tort, which is a wrongful act leading to civil legal liability. In this case, Jackie, by negligently causing harm, is the tortfeasor.

• Misdemeanant: This term refers to someone who has committed a misdemeanor, which is a type of criminal offense. Since the context is a civil negligence action, this term is incorrect.

• Suspect: This term is used in criminal law to refer to someone thought to have committed a crime. It is not applicable in a civil negligence case.

• Tortuga: This is not a legal term related to negligence. It is the Spanish word for "turtle" and is irrelevant in this context.