After administering a written test, what should the instructor do?

The correct choice emphasizes the importance of maintaining the integrity of the assessment process. Once a student submits their answers, they should not be allowed to change them. This principle is crucial in evaluating a student's understanding of the material accurately. Allowing changes may lead to issues related to fairness and transparency, as some students might reconsider their answers based on information shared after submission, thereby undermining the assessment's reliability.

Maintaining a strict cutoff where answers cannot be altered ensures that each student's performance reflects their knowledge and readiness as of the time of the test. This approach upholds the standards of testing and ensures consistency across all students' performances, which is crucial for assessing collective learning outcomes.