Which format allows linking a commit to an issue in GitLab?

The correct format for linking a commit to an issue in GitLab is the one that uses the hashtag followed by the issue number, denoted as #issue_number. This syntax is commonly used in GitLab to create direct references to issues within various discussions, commit messages, and merge requests.

When a commit message contains this format, GitLab automatically recognizes it and creates a link to the referenced issue. This enhances traceability and context by allowing team members to easily navigate between related commits and issues.

The other options do not follow the correct syntax recognized by GitLab for linking commits to issues, thus they would not produce the desired automatic linking feature. This correct usage of the hashtag is an integral part of maintaining organized project management within GitLab, aligning commits with the progress on issues and facilitating better collaboration among team members.