Gatekeeper is designed to help ensure that only trusted software runs on a Mac. For software downloaded from outside the App Store, Gatekeeper checks factors such as developer identification, notarization, and whether the software has been altered. Apple also documents that Gatekeeper requests user approval before downloaded software is opened for the first time and tracks the provenance, or origin, of files written by downloaded software. That combination matches option D. Gatekeeper does not automatically reject all software distributed outside the App Store because appropriately signed and notarized applications from identified developers can run. Apple also does not simply review unsigned software as described in option C. Gatekeeper combines code-signing validation, notarization checks, provenance tracking, and first-launch user approval to reduce the risk of users unintentionally executing unsafe software.

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