A duty performed by the instructor during a written test is:

The responsibility of ensuring the environment remains quiet and safe for the students is vital during a written test. This duty emphasizes the instructor's role in creating an appropriate testing atmosphere, which is crucial for the students' focus and performance. A quiet environment helps minimize distractions, allowing students to concentrate fully on the test questions. Ensuring safety is equally important; it encompasses both physical safety and emotional security, fostering a space where students can perform to the best of their abilities without fear of disturbances or concerns.

Other options do not align with the instructor's duties during a written test. Grading tests immediately would compromise the integrity of the testing process, as it may lead to hasty conclusions or errors. Providing answers to students is not permissible, as it undermines the assessment's purpose and fairness. Leaving the room would not support a conducive testing environment, as it could lead to disruptions or security issues, further negating the obligations of the instructor during such an evaluation.