Can someone turn down that app?

You are converting some video from one format to another, and you want to participate in a videoconference at the same time. Unfortunately, the video conversion is causing the videoconference feed to stutter. What Windows utility can you use to lower the priority of the conversion process?

A) Device Manager

B) Event Viewer

C) Task Manager

D) Services

E) If you move your head back and forth really fast, you can hardly see the stuttering