What is the role of the reference sample during a test?

The reference sample plays a crucial role in ensuring the accuracy and reliability of the breath test conducted by the Intoxilyzer 9000. It is a known sample with a predetermined alcohol concentration that acts as a benchmark against which the results of the individual's breath sample are compared. This comparison is essential to verify that the instrument is functioning properly and that the readings produced during the breath test are accurate.

By measuring the reference sample, the device can detect any discrepancies in the readings of the breath sample taken from a suspect. If the results of the reference sample and the subject's sample show significant variation, it could indicate a malfunction or error in the testing process, prompting further investigation or retesting. This step is crucial in maintaining the integrity of the testing procedure and ensuring that the results can be trusted for legal and law enforcement purposes.

The other options describe roles that do not accurately reflect the function of the reference sample. While some options suggest alternative uses for the sample, none encapsulate its primary purpose, which is focused on accuracy verification through direct comparison with the breath sample.