A scientist claims that a certain chemical will make fabric waterproof. Which option describes a controlled experiment that will produce evidence that will
support or refute her claim?
A. One group of fabric is treated with the chemical, and the other
group is not. Then each group is exposed to water.
B. One group of fabric is treated with a small amount of the
chemical, and the other group is treated with a large amount. Then
each group is exposed to water.
C. Two groups of fabric are treated with the chemical. One group is
cotton and the other is polyester. Then each group is exposed to
water.
D. Two groups of fabric are treated with the chemical. Then one
group is exposed to a small amount of water, and the other group
is exposed to a large amount.