What happens if a subject fails to observe the 20-minute waiting period before a test?

The correct answer is that the results may be compromised due to potential consumption of substances. The Intoxilyzer 9000 requires a 20-minute waiting period to ensure that the subject does not have any residual mouth alcohol from recent consumption of alcohol or other substances that could affect the accuracy of the test results. If a subject does not observe this waiting period, there is a risk that any alcohol present in their mouth could artificially elevate the blood alcohol concentration (BAC) reading. This can lead to a falsely high reading, which wouldn't accurately reflect the subject's actual BAC, thus compromising the test's validity.

The other choices do not align with the procedures and outcomes associated with the waiting period. The test cannot provide valid results without this observation, immediate arrest isn’t a direct outcome of the waiting period violation, and repeating the test after only 10 minutes does not resolve the issue of residual mouth alcohol, which is specifically addressed by the full 20 minutes.