What documentation must security schools maintain regarding handgun proficiency?

The correct answer highlights the importance of maintaining records of the required proficiency, specifically for the training and assessment of individuals in handgun use. This documentation is crucial for ensuring that all students meet the established standards for firearm handling and safety as part of their security training.

Maintaining records of proficiency demonstrates compliance with state regulations and provides a verifiable way to confirm that the training provided was effective and that students have indeed achieved the necessary skills to operate a handgun safely and competently. This documentation is essential in case of audits by regulatory agencies, and it also contributes to the overall accountability of the security school.

The other options, while related to the activities of security schools, do not specifically address the critical need for proficiency documentation. Certification of completion indicates that a student finished a course but does not necessarily reflect their skill level with firearms. Employee files of instructors are important for ensuring that qualified personnel are teaching, but they do not pertain directly to the student proficiency records. Attendance sheets track participation but do not provide evidence of skill competency in handling a handgun. Therefore, the emphasis on proficiency records is key to ensuring responsible and effective training in firearm skills.