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Stage 1
Answer 4 questions correctly in a row.
The passage below describes an experiment.

a fire burning a prairie
- Dr.
Wells was the land manager for a prairie. The prairie had become overrun by unwanted grasses that were crowding out other plants. Dr. Wells thought she could use fire to remove the unwanted grasses. - Dr.
Wells marked off six plots within a large area of the prairie. In three of the plots, she set a carefully controlled fire to burn all of the plants once each year for three years. In the remaining three plots, she did not set any fires. A year after the last fire, Dr. Wells estimated the percentage of area covered by unwanted grasses in each of the six plots.
In this experiment, which were part of a control
group?
the plots with fires
the plots with no fires
ref_doc_title.
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