The correct answer is 'Retrieve updates from a remote repository.' This answer is correct because the Git command in question is designed specifically to fetch and merge changes from a remote repository into the current branch in a local repository. 'Push changes to a remote repository' is incorrect as this is the purpose of the git push command, which transmits local branch updates to the corresponding remote branch. 'Merge a remote branch into the current branch' doesn't necessarily involve remote communication and could be done with local branches, thus it is also incorrect. 'Revert a local commit' pertains to commands such as git revert or git reset, which are used to undo local changes.