What range is indicated by the vacuum gauge wide green arc at sea level to 15,000 feet?

The correct answer reflects the vacuum gauge's operational limits, which are critical for ensuring that the King Air 350's instruments and systems, reliant on vacuum pressure, operate properly. The wide green arc on the vacuum gauge represents the acceptable vacuum pressure range for the aircraft, specifically set between 4.3 to 5.9 inches of mercury (Hg) at sea level up to 15,000 feet.

Maintaining vacuum pressure within this range is essential for the proper functioning of gyroscopic instruments. If the vacuum levels fall below or exceed this range, it can lead to erroneous instrument readings, which could compromise flight safety. Therefore, understanding and monitoring this range is vital for pilots operating the King Air 350.

In contrast, the other options do not accurately match the specifications provided for the vacuum gauge's green arc, leading to the conclusion that they fall outside of the acceptable limits for safe operation.