Which of the following best describes the FSO's primary responsibility?

The primary responsibility of a Facility Security Officer (FSO) is to ensure the protection of classified information. This role involves implementing security measures, conducting risk assessments, and ensuring compliance with government regulations related to the handling and safeguarding of classified materials. The FSO plays a critical role in establishing and enforcing security policies to prevent unauthorized access to sensitive information, which is vital for protecting national security interests.

In addition to protecting classified information, the FSO is responsible for training personnel on security protocols, conducting investigations of security incidents, and collaborating with government agencies to maintain security standards. This central focus on safeguarding classified information is essential for the FSO's role within the National Industrial Security Program (NISP), making it the correct answer in this context.