What is the push notification service used by Android?

Firebase Cloud Messaging (FCM) is the correct answer because it serves as the primary push notification service for Android devices. FCM allows developers to send messages and notifications to Android applications. It is a cross-platform messaging solution that not only supports Android but also iOS, making it a versatile choice for app developers looking to reach users across different devices.

In contrast, APNs (Apple Push Notification service) is specifically designed for iOS devices and cannot be utilized on Android. PushKit is an iOS-specific framework that aids in managing push notifications in the background, but it does not apply to Android. The Local Notification System refers to notifications that are triggered locally on the device without server involvement, which also does not involve external push services.

In summary, FCM is integral for facilitating communication between your server and your Android app, enabling timely notifications to reach users effectively.