Final answer:
The stakeholder register is completed first in project management, serving as the foundation for creating the stakeholder management plan.
Step-by-step explanation:
In project management, the output that is completed first is the stakeholder register. This is a document or database where all pertinent information regarding project stakeholders is recorded. It includes details such as the stakeholders' names, contact information, their role in the project, and their impact on the project. After identifying and analyzing stakeholders through the stakeholder register, the project team can then create the stakeholder management plan. This is a strategy document that outlines how to engage and communicate with stakeholders to gain support and manage expectations. Therefore, the correct answer is (1) The stakeholder register).