Jenny was worried about how some pollutants in a lake near her home were affecting the levels of dissolved oxygen in the water, so she designed the
following experiment. First she collected five 10-gallon aquariums and filled each
with water from her tap. Then, she tested the initial oxygen level of the tap water.
Next, she put a tablespoon of different pollutants, including gasoline, cooking oil,
paint, and lawn fertilizer, in each of four of the tanks. She stirred those four tanks
for 1 minute each to help the pollutant dissolve or spread out in the tank. Lastly,
she tested the oxygen level in each tank once every hour and recorded her
results in a table. What is the independent variable in Jenny's experiment? *
the amount of pollutant put in each tank
Ο Ο Ο
initial oxygen level in the tank without the pollutant
pollutant in each tank
levels of oxygen in each tank