Which One of the Following Is the Primary Use of Google

Multiple Choice

Which one of the following is the primary use of Google Play Licensing Service?

A) To verify that the user did actually pay for the application.
B) To check the number of time user has paid for the application
C) To let the free application start downloading APK expansion files if your application needs them.
D) To let the paid application start downloading APK expansion files if your application needs them.