Which form is used to perform the personnel reliability screening process required when a unit commander delegates authority to personnel?

The correct form used to perform the personnel reliability screening process when a unit commander delegates authority to personnel is DA Form 7708. This form is specifically designed to evaluate an individual's reliability and trustworthiness, which are crucial in maintaining operational security, safety, and mission effectiveness in military environments. By using DA Form 7708, leaders can ensure that personnel entrusted with sensitive duties meet the necessary standards and criteria established for reliability screening.

This form's design allows commanders to document the assessment of personnel, thereby formalizing the delegation process while maintaining accountability. The other forms listed serve different purposes: DD Form 626 is related to the transport of hazardous materials, Standard Form 86 is used for security clearance investigations, and DA Form 3151 pertains to the control of property, which does not align with the specific needs of personnel reliability screening.