Two students designed an experiment that investigated the effect of different brands of fertilizer on tomato plant growth. There were a total
of three groups. Each student treated one group of plants with no fertilizer, a second group of plants with Brand X fertilizer, and a third
group with Brand Z fertilizer. Student A planted his tomatoes wherever soil was available. Some were in a spot that was shady most of the
day and some were in sunlight; some were in sandy soil and some were in rocky soil; some were in pots and some were in the ground.
Student A watered the plants whenever he remembered. Student B planted all of her tomatoes in the same kind of soil, in a location where
all the plants received the same amount of light, and made sure that all the plants received the same amount of water on a regular schedule.
Which student's results are more likely to be accurate?
Student A
Why?
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Which group is the control group?
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What are the control variables in the experiment?
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