converting sound to electrical impulses receiving transmitted electrical signals changing electrical impulses into sound sending electrical signals through a circuit
I gave my students this multiple choice question: Which of the following best describes the function of an encoder in a telephone communication system?

Only one answer is correct among these 4 choices:
- converting sound to electrical impulses
- receiving transmitted electrical signals
- changing electrical impulses into sound
- sending electrical signals through a circuit

Could you tell me which one is correct?

converting sound to electrical impulses