You are developing a Windows Store app for devices connected to AC power.
The app must meet the following requirements:
The app must download movie reviews from a web service once per hour.
The app must have new movie reviews ready for the user when the user interacts with the app.
The app cannot interact with the lock screen.

You need to ensure that the web service is called periodically whether the app is running or
suspended.
What should you do?

A.
Use the ThreadPoolTimer.CreatePeriodicTimer() static method to periodically call the web service
to get new movie reviews for display.

B.
Implement the IBackgroundTask interface to make the service call and then register a
PushNotificationTrigger object to run the background task when the new reviews are available.

C.
Implement the IBackgroundTask interface to make the service call and then register a TimeTrigger
object to run the background task every hour.

D.
Implement the IBackgroundTask interface to make the service call and then register a
MaintenanceTrigger object to run the background task every hour.

Explanation:
http://msdn.microsoft.com/enus/library/windows/apps/windows.applicationmodel.background.ibackgroundtask.aspx
http://msdn.microsoft.com/enus/library/windows/apps/windows.applicationmodel.background.maintenancetrigger.aspx