The stakeholder register is the key output of the Identify Stakeholders process. It not only contains the names of the project stakeholders but also their goals, expectations, concerns, and other such details. The stakeholder register helps to plan, manage, and communicate with the stakeholders effectively and efficiently. The other options are not outputs of the Identify Stakeholders process, but inputs or outputs of other processes. The scope baseline, the project charter, and the project scope statement are all inputs or outputs of the Project Scope Management knowledge area, not the Project Stakeholder Management knowledge area. References:

Identify Stakeholders Process and Stakeholder Register

Chapter 13 - Stakeholder Management Flashcards

How to Identify Stakeholders in Project Management?