POSSIBLE POINTS: 1 Please read the example carefully and choose the best answer below.
Marie notices that the current cleaner she is using on her shower is not cutting through the hard water build-
up that has accumulated. She decides to purchase 3 other cleaners to see if one of them will do a better job
of cutting through the stains. Marie places masking tape in the dry shower to create 5 sections for her
experiment. She sprays 3 squirts of one cleaner per section and leaves the remaining section untouched to
compare her results. After 30 minutes, and without scrubbing any of the cleaner in, she records her
observations.
In this example what is the independent variable?