Must the operator check the blue box and type "YES" to confirm the completion of the 15-minute waiting period?

The correct answer is that the operator must check the blue box and type "YES" to confirm the completion of the 15-minute waiting period. This step is crucial in the breath testing process, as Texas law requires that a subject must be observed for a minimum of 15 minutes prior to testing to ensure that they do not consume any substances that could affect the results.

Checking the box and confirming this observation provides an official record that the protocol for the waiting period was followed. This confirmation is important for the integrity and validity of the test results, as any violations of the observation requirements could lead to challenges regarding the admissibility of the test results in court. By adhering to this procedure, the operator ensures compliance with the established testing protocols, maintaining the credibility of the testing process.

Other options suggest scenarios where confirmation may not be necessary or depends on prompting, which is inaccurate because the operator must actively affirm that the waiting period was completed correctly to ensure legal compliance and accurate test outcomes.