Phase 1: Question Interpretation.
The query seeks the managerial activity that is perpetually ongoing due to the emergence of new positions and employee attrition.
Phase 2: Option Evaluation.
- Strategic Planning: Encompasses objective setting and strategic formulation, but its continuous nature is not as direct in this scenario.
- Organizing: Pertains to the arrangement of assets and duties, yet it is not a continuous function akin to personnel management.
- Staffing: Denotes the procedures of recruitment, development, and retention of personnel. This is an incessant activity as enterprises must substitute personnel and adapt to evolving demands.
- Controlling: Involves oversight and modification, but it lacks the continuous characteristic of staffing.
Phase 3: Resolution.
The appropriate response is Staffing, as it represents a perpetual undertaking within organizations owing to employee turnover and evolving corporate requirements.
Determinative Response: \[\boxed{\text{The correct answer is (3) Staffing.}}\]