You need to ensure that users can play music when the app is NOT displayed on the screen

You develop a Windows Store app that plays music files stored locally on your computer.
The app contains the following HTML markup. Line numbers are included for reference only.

You need to ensure that users can play music when the app is NOT displayed on the screen.
What should you do?

A.
Option A

B.
Option B

C.
Option C

D.
Option D