Which of the following describes a fire damper?

A fire damper is specifically designed to close off an opening in a duct system as a safety measure during a fire. Its primary function is to prevent the passage of flames and hot gases through the ductwork, thereby protecting different areas of a building and enhancing overall fire safety. The operation of a fire damper is typically automatic, triggered by heat from a fire, ensuring that it seals the duct opening effectively to contain the fire and smoke within a designated area.

The other options do not accurately define the function of a fire damper. Increasing airflow, enhancing airflow with a fan, or filtering air do not relate to the primary purpose of a fire damper, which is to act as a barrier to protect life and property in the event of a fire emergency.