Answer the following question given this paragraph: 

One reason radiation is dangerous is that it can’t be detected with the senses. You normally can’t see it, smell it, hear it, or feel it. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one in Figure below , has a tube that contains atoms of a gas. If radiation enters the tube, it turns gas atoms to ions that carry electric current. The current causes the Geiger counter to click. The faster the clicks occur, the higher the level of radiation. You can see a video about the Geiger counter and how it was invented at the URL below.


Q: Geiger counters can be used to detect what, in general?

 Choices:

- seismic load

- convection

- evaporation

- radiation

A:
radiation
