Final answer:
To register a broadcast receiver in an Android app, add a receiver element to the AndroidManifest.xml file, specifying the receiver's class name and optional intent filters.
Step-by-step explanation:
To register a broadcast receiver in your Android application, you need to add a <receiver> element within the AndroidManifest.xml file. This element should define the broadcast receiver with its fully qualified class name and optionally can specify various intent filters that determine the types of broadcasts the receiver should listen to. For example:
<receiver android:name=".MyBroadcastReceiver">
<intent-filter>
<action android:name="android.intent.action.BOOT_COMPLETED" />
</intent-filter>
</receiver>
This <receiver> tag specifies that the MyBroadcastReceiver class should receive intents that match the action 'BOOT_COMPLETED'. Note that some broadcast receivers require appropriate permissions to work, which must also be declared in the manifest.
The complete question is: What element do you add to a project's AndroidManifest.xml file to register a broadcast receiver? is: