Which arrangement ensures a unit retains control over personnel logistics while attached to another unit?

The arrangement that ensures a unit retains control over personnel logistics while attached to another unit is Administrative Control (ADCON). This type of control is crucial for maintaining oversight of personnel management, including assignments, promotions, and other administrative functions, even when operating under the command of another unit.

When a unit is attached to another for operational purposes, it often operates under Operational Control (OPCON) or Tactical Control (TACON), which primarily focus on the execution of specific missions and tactical responsibilities. However, these forms of command do not provide the same level of control over personal logistics, which is where ADCON comes into play.

ADCON allows the unit to manage its administrative matters independently, ensuring that logistical and personnel-related processes remain intact and comply with the home unit's policies and standards. This is particularly important for maintaining unit readiness and morale, as personnel logistics often directly impact mission effectiveness.

DIRLAUTH refers to direct liaison authorized, which facilitates inter-unit communication but does not pertain to control over logistics or personnel management. Thus, ADCON is the most appropriate choice for ensuring that a unit retains control over its personnel logistics while functioning within another unit's operational structure.