Answer the following question given this paragraph: 

You generally can’t see, smell, taste, hear, or feel radiation. Fortunately, there are devices such as Geiger counters that can detect radiation. A Geiger counter, like the one pictured in the Figure below , contains atoms of a gas that is ionized if it encounters radiation. When this happens, the gas atoms change to ions that can carry an 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: What does the geiger counter detect?

 Choices:

- vibration

- convection

- moisture

- radiation

A:
radiation
