What is the function of a Milestone in GitLab?

A Milestone in GitLab serves to organize related issues and merge requests by delivery periods, making option B the correct choice. This functionality allows teams to track progress towards specific goals or deadlines within a project. By grouping issues and merge requests under a common milestone, teams can better visualize and manage their workload, set clear objectives, and assess performance regarding the timelines agreed upon for project phases. This promotes better collaboration and efficiency among team members as they can see what needs to be completed by a specific date.

In contrast, while outlining broad project strategies, evaluating team efficiency, or managing user onboarding can be important aspects of project management and development, they do not specifically define the purpose of milestones in GitLab. Milestones focus explicitly on tracking deliverables and managing timelines within the software projects.