Which of the following is an example of a primary air sampling calibration device?

The Gilibrator is an example of a primary air sampling calibration device because it is specifically designed to calibrate air sampling pumps, ensuring that they operate at the correct flow rates. Primary calibration devices like the Gilibrator provide a direct measurement of volumetric flow rate, allowing for precise adjustments to be made to the sampling equipment. This is essential in occupational hygiene to ensure that air samples collected accurately reflect the concentration of contaminants in the work environment.

In contrast, other options such as a rotameter, pump, or filter holder serve different roles in the air sampling process. A rotameter is used to measure the flow rate but does not provide the primary calibration necessary for accuracy. A pump is a crucial component of the sampling system, responsible for moving air through the sampling medium, but it requires calibration to ensure its flow rate is accurate. Lastly, a filter holder is used to support filters during sampling but does not involve the calibration process itself. Thus, the Gilibrator's specific function in calibrating sampling devices makes it the correct choice as a primary air sampling calibration device.