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 Sound waves are mechanical waves". So, what's the best answer to the question?
Pick from:
[1]. books.
[2]. Electrical energy.
[3]. electromagnetic energy.
[4]. nails.
[5]. chemical messengers.
[6]. mechanical waves.
[7]. encoded information.
[8]. ice.
[6].