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.
Finally, she tested the oxygen level in each tank once every hour and recorded her results in the table below.
Tank
Pollutant
in water
Initial
O2 level
(without pollutants)
O2 level O2 level
after 1 hour after 2 hours
1 none
2 gasoline
3 cooking oil
4 paint
5 lawn fertilizer
What is the dependent variable in Jenny's experiment?
OA. initial oxygen level in tank without pollutant
OB. levels of Oz in each tank
OC. amount of pollutant put in each tank
OD. pollutant in each tank