The tool of choice to accurately check the inlet restriction of a dry air filter would be a?

The tool that is best suited for accurately checking the inlet restriction of a dry air filter is a restriction gauge. This gauge is designed specifically to measure the difference in pressure across the air filter, providing a clear indication of how much airflow is being impeded due to dirt or debris buildup. A restriction gauge offers a direct reading of the pressure drop in inches of water or another unit, which correlates to the effectiveness of the air filter and helps technicians determine when the filter needs to be cleaned or replaced.

Using a mercury-filled manometer or a water-filled manometer, while they are both capable of measuring pressure differences, is not ideal for this application. These tools can offer precise measurements, but they require more setup and handling than a restriction gauge. Additionally, they are not specifically designed for the purpose of evaluating air filter condition, making them less practical in this scenario. A trouble light, on the other hand, serves a completely different function related to illumination and does not provide any data on air filter status. In summary, the restriction gauge is the most efficient and purpose-built tool for assessing air filter inlet restriction.