Which answer accurately captures the security risk of an Android ContentProvider with android:exported="true" and no android:permission set?

• A.An exported ContentProvider without a permission is reachable only by apps signed with the same key, and the platform derives that restriction from the signing certificate recorded at install (PackageManagerService compares the certificates on every query); the implicit protection covers reads and writes alike. No manifest permission is needed.
• B.With exported="true" and no permission, any installed app (regardless of privileges) can query, insert, update, and delete data in the ContentProvider; this exposes all data the provider controls (contacts, messages, files) to unauthorized apps without any access control verification.
• C.Without android:permission set, the ContentProvider inherits the INTERNET permission for its gate, and access narrows to apps able to open a socket (the framework substitutes the default during manifest parsing); a purely local app is refused at the query boundary. All other callers pass the check.