Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

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.


Question: What is harmless water vapor, for a powerplant?
steam
The steam produced by a powerplant.