Which series tests the trainee's readiness to perform a designated task?

The selection of Series #300 reflects the correct understanding of the testing methods used to assess a trainee's competency and preparedness for specific tasks within the training structure. This series is specifically designed to evaluate an individual’s ability to perform tasks that align with their training objectives and responsibilities.

Series #300 ensures trainees demonstrate their proficiency before advancing or being assigned actual tasks, which is crucial in maintaining operational readiness and ensuring that all personnel are equipped with the necessary skills. This testing format emphasizes practical application rather than theoretical knowledge, which is essential in a hands-on training environment like the USNSCC.

In contrast, the other series do not directly focus on task performance readiness as effectively as Series #300 does, thereby making them less suitable for measuring the readiness to perform designated tasks. The distinct nature of Series #300 in prioritizing performance readiness is why it is identified as the correct answer.