A user, Anne, downloaded an Android app directly from a developer's website and is unable to install it on her smartphone. Which of the following will allow Anne to install the app?

Installing a recovery image replaces the system recovery partition and is unrelated to granting permission to install third-party APKs.

Android's default security setting restricts app installation exclusively to the Google Play Store, treating APKs from other sources as unknown and blocking them. Enabling 'Allow apps from unknown sources' (or 'Install unknown apps' on Android 8+) grants permission to install APKs sourced from outside the official store. This setting is found in Security or Privacy settings and is the only change required to sideload a developer-provided APK.

Near field communication is a short-range wireless technology used for data transfer and payments, with no effect on app installation permissions.

Root access grants elevated system privileges but is not required to sideload an APK - enabling unknown sources alone is sufficient for installation.