Task: Text Completion
Input (English): Young boys are shown doing a karate demo in front of the judges. they <sep> (A) practice quickly how to execute a martial art using their hands in steps while with their heads lowered. (B) use a black belt and a nunchaku. (C) practice with swords and perform several different moves. (D) move back and forth and front to back performing various punches.
Output (English): D