You connect your computer to a multimedia projector. When you play a video， you cannot hear the audio.  You need to ensure that the projector provides audio and video playback.  What should you do？（）

• A、Configure the computer to use the default sound scheme.
• B、Enable the Presentation Settings option. Adjust the volume settings as appropriate.
• C、In the Line In Properties dialog box， clear the Allow applications to take exclusive control of this device check box.
• D、In the Presentation settings dialog box， select the I always give a presentation when I use this display configuration check box.