A __________ failure will require the candidate to attend and satisfactorily complete the basic course of instruction for certification of a breath testing operator.

A subsequent failure will necessitate that the candidate attend and satisfactorily complete the basic course of instruction for certification as a breath testing operator. This means that if a candidate fails a certification examination after having previously met the requirements and passed, they will need to return to the fundamental training to strengthen their knowledge and skills before attempting the certification again.

This process ensures that individuals remain proficient and up-to-date with the requirements and procedures involved in breath testing. It emphasizes the importance of maintaining high standards in the operation of breath testing equipment, such as the Intoxilyzer 9000, to ensure accurate and reliable results.

Other options refer to different types of failures that do not specifically require a return to the basic training course under the established guidelines, making "subsequent" the correct choice in this context.