You are designing a Windows Phone 7 application that refreshes data from the network. The application will retrieve data when the phone is active. You need to stop network activity when the screen on the phone is locked. What should you recommend?

A.
Handle the Obscured event of the applications root PhoneApplicationFrame object.

B.
Handle the Unobscured event of the applications root PhoneApplicationFrame object.

C.
Handle the Application_Deactivated event of the applications root PhoneApplicationFrame object.

D.
Set the ApplicationIdleDetectionMode property of the applications PhoneApplicationService object to Disabled.