Question from the Android test

In the onDestroy() method. This is the last callback called by the Activity before being killed. This way I am sure that my backup will only be done once.

In the onStop() method. I am sure that this callback will always be called and it is likely to be returned only a few times.

In the onPause() method. This is the only callback about which I have the express guarantee that it will be called. It doesn't matter if this callback is called often.

In the onSaveIntanceState(Bundle bundle) method. This callback has been expressly made available by the system for this type of data backup mechanism.