You are presented with the quiz "What can be used for communication by animals?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "sound can be used for communication by animals" and "sound vibrations have different frequencies". So, what's the best answer to the question?
OPTIONS: I. electricity; II. energy; III. Telephones.; IV. Vibrations.; V. Stuffed animals.; VI. messengers; VII. courtship; VIII. Cellular communication.;
Answer:
IV.