Answer the following question given this paragraph: 

Steam rises from the cooling towers of this nuclear power plant. The steam is only harmless water vapor. Unlike a power plant that burns fossil fuel, a nuclear power plant doesn’t release pollution into the air. That’s because a nuclear power plant produces power by nuclear fission, a type of nuclear reaction.


Q: What is harmless water vapor, for a powerplant?

 Choices:

- wind

- plasma

- fog

- steam

A:
steam
