Answer: C. Experimental group
Step-by-step explanation:
A controlled experiment is a scientific test in which a single variable can be directly manipulated to know the effect of manipulation over the variable under study. A control variable is used over which no manipulation is performed. It is kept as a benchmark for comparison of observations by using the control and experiment group in an experiment.
An experiment group is a set of independent variables over which the tests are performed in a controlled experiment.