Final answer:
A- a spring in the unmetered fuel chamber to supplement the action of normal metering forces. On an engine equipped with a pressure-type carburetor, fuel supply in the idling range is ensured by a spring in the unmetered fuel chamber.
Step-by-step explanation:
On an engine equipped with a pressure-type carburetor, fuel supply in the idling range is ensured by the inclusion of a spring in the unmetered fuel chamber to supplement the action of normal metering forces.