Change management is the structured approach to transitioning individuals, teams, and organizations from a current state to a desired future state. When deploying a new enterprise-wide tool, the primary challenge is not just the technical implementation but ensuring user adoption, minimizing resistance, and integrating the tool into business processes to realize its intended value. Change management directly addresses this "organizational impact" by focusing on communication, stakeholder engagement, training, and managing the human elements of the transition. This ensures the technology is not only deployed but also effectively embraced, which is a key responsibility of a CIO in delivering value.

B. project management: Project management focuses on the technical execution of the deployment—delivering the tool on time, within budget, and to scope—but does not primarily address the human and cultural adoption aspects.
C. risk management: While poor user adoption is a risk, risk management is a broader discipline. Change management is the specific set of practices used to mitigate the particular risks associated with organizational impact.
D. resource management: This discipline is concerned with the allocation and scheduling of assets (e.g., personnel, budget, equipment) for the project, not with managing the behavioral and procedural shifts across the organization.

1. ISACA, COBIT® 2019 Framework: Governance and Management Objectives, 2018. The process BAI05 Managed Organizational Change is defined with the purpose to "Prepare and commit stakeholders for business change and reduce the risk of failure." It emphasizes activities such as communicating the desired vision, empowering role players, and embedding new approaches, which are all core to managing organizational impact. (Ref: COBIT 2019, BAI05, p. 135).

2. ISACA, CGEIT Review Manual, 8th Edition. The manual emphasizes that for IT-enabled investments to deliver value, the resulting changes to business processes and employee roles must be managed effectively. Domain 4, "Value Optimization," highlights that benefit realization is contingent on successful business change, which is the primary goal of change management. (Ref: CGEIT Review Manual, 8th Ed., Domain 4: Value Optimization).

3. Aladwani, A. M. (2001). Change management strategies for successful information system implementation. Business Process Management Journal, 7(3), 266-275. This academic paper argues that overlooking the human and organizational aspects of IT implementation is a primary cause of failure. It posits that a systematic change management strategy is essential to manage resistance and ensure user acceptance, directly addressing the "organizational impact." (DOI: https://doi.org/10.1108/14637150110392764).