You are presented with the quiz "What does a radio use to make vibrations?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "aradio converts electrical energy into vibrations" and "electric energy is stored in batteries". So, what's the best answer to the question?

Possible answers:
1). waves;
2). rays or beams;
3). a battery;
4). an object;
5). barrel-shaped;
6). nerves;
7). Loud noises;
8). it needs them;
The answer is:
3).