Answer: B
Correct answer: periodically saves a temporary copy so work can be recovered after a crash
AutoRecover writes a temporary copy of open documents at intervals - ten minutes by default - so that if Word or the machine crashes, the work can be recovered when Word next starts. The interval is set in File, Options, Save. It is important to understand what it is not. It does not save the document: the file on disk is untouched until Ctrl + S is pressed, and the AutoRecover copy is discarded when a document is closed normally. It is a crash safety net, not a substitute for saving. The related setting, Keep the last autosaved version if I close without saving, preserves that copy for a time and makes it reachable through Recover Unsaved Documents at the foot of the Open pane. AutoSave is a different and newer feature: for files stored on OneDrive or SharePoint it writes changes continuously to the real file, with version history available.