Which of the following is a criterion for changing locks and combinations?

Changing locks and combinations is a critical aspect of maintaining security in any facility, particularly in military settings. The correct answer, which indicates that locks and combinations should be changed annually or upon the departure of personnel, aligns with established security practices.

Changing locks annually helps mitigate the risk of unauthorized access due to key distribution over time or any potential security breaches that may occur. Additionally, altering locks upon a staff member's departure ensures that former employees do not retain access, which is crucial for safeguarding sensitive areas and information. This practice greatly reduces the chance of insider threats and maintains overall security integrity.

While changing locks every six months or after any incident can be effective in certain scenarios, these options may be considered excessive or impractical in regular operations. Likewise, changing locks every five years may not be frequent enough to ensure optimal security given the potential for changing personnel and risks over time. Therefore, the annually or upon departure criterion strikes a balance between security needs and operational practicality.