A controlled experiment is one in which .

A) there are at least two groups, one differing from the other by two or more variables.

B) the experiment is repeated many times to ensure that the results are accurate.

C) there is one group for which the scientist controls all variables.

D) the experiment proceeds at a slow pace to guarantee that the scientist can carefully observe all reactions and process all experimental data.

E) there are at least two groups, one of which does not receive the experimental treatment.

E) there are at least two groups, one of which does not receive the experimental treatment.

Explanation:

A controlled experiment is an experiment that is manipulated by the scientist to suits his methods. They are conducted to test a single variable at a time. It helps to minimize the random effect of wild environment on the experiment.

In a controlled experiment there are two groups; one group receive treatment in certain proportion it is referred to as controlled group while the other group are exposed to the standard environment known as experimental group.

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