Which statement describes a controlled experiment? A. It includes two groups, both of which are exposed to the factor
being tested
O B. It includes two groups, neither of which is exposed to the factor
being tested.
O C. It includes a group exposed to the factor being tested and a group
that is not exposed to the factor being tested.
D. It includes a group exposed to one of the factors being tested and
a group that is exposed to another of the factors being tested.