What kind of changes does a user need to stage before committing in Git?

In Git, the staging area (also known as the index) is used to prepare changes before they are committed to the repository. When a user stages files, they are explicitly selecting which changes they want to include in the next commit. This selective inclusion is crucial for maintaining a clear and coherent project history. By staging only the selected files containing changes, the user can choose to commit only specific modifications rather than all changes made across the repository. This capability allows developers to structure their commits logically, enhancing the clarity and organization of the project's commit history.

In contrast, the other options do not represent the correct process for staging changes: old and outdated files do not have relevance in the context of staging for a commit, all files in the repository would imply including every change, which contradicts the purpose of selective staging, and files that have been deleted are handled differently, as Git tracks deletions but does not require them to be staged for a commit to record the deletion.