What is the process under which Airmen test after initial selects have been made?

The in-system supplemental promotion process is the correct choice because it specifically refers to the method used for Airmen who are already in the promotion cycle and are testing for additional promotion opportunities after the initial selections have been determined. This process allows for those who were not selected in the first round of promotions to still have a chance to be promoted based on additional testing and evaluations.

This approach ensures that Airmen have a fair opportunity to advance in their careers, even if they were not included in the initial selectees due to various factors. It is designed to recognize performance and potential of those who may not have been part of the initial selection.

In contrast, the other options do not accurately describe this specific situation. Performance level assessments generally evaluate Airmen’s performance levels but aren't aimed at the supplemental promotion process. Standardized testing procedures refer to general testing methods and do not specifically address supplemental promotion. Similarly, the promotion continuation process relates to maintaining select status rather than providing additional opportunities for promotion after initial selects.