Answer the following question: You are presented with the quiz "What uses ears to hear?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "hearing is used for sensing sound by animals" and "sound waves enter the ear, and are then amplified". So, what's the best answer to the question?

Pick your answer from:
1). Stereos.
2). humans.
3). TVs.
4). Animals.
5). Mammal.
6). organisms.
7). pigeons.
8). Plants.
Answer:
4).