Why did the introduction of sound into film initially impede the movement of actors?

12.     to produce a textured purée, you would use a/an a. food processor. b. wide-mesh sieve. c. immersion blender d. food mill. student a   incorrect which is correct answer?

This is just a little thing i just did for fun! hope you enjoy! a: ~what would you first grand if your house was onfire? b: ~what do you first notice on a person? c: ~ what are some challenges you think the next generation will face? d: ~what is the most embarrassing moment in life? e: ~what is your favorite artists? //music//f: ~what are some bad habits you can't stop doing? , but you know you need to stop on them.i really hope you had fun doing this, or not doesn't matter, but if you want more from me contact me! bye now//i can't wait to see some results//ㅋㅋㅋㅋㅋ나를 따라라! ^^(i'm going to put this under arts, even though it's not, so yeah)

For the difference command to work, what needs to happen?