In an experiment, a group identical to a control group except for one factor and compared with the control group.

• A. Control Group
• B. Experimental Group
• C. Qualitative Observation
• D. Hypothesis

Answer: (B)

In experimental design, you isolate the effect of a single factor by comparing two groups that are identical in every way except for that factor. The group that matches the control in all aspects except for the variable being tested is the experimental group. By comparing its outcomes with the control, you can attribute any observed difference to that factor. The control group provides the baseline under normal conditions. A qualitative observation is a type of data collection, not a defined experimental group. A hypothesis is a proposed explanation to be tested, not a group in a study. The described setup refers to the experimental group.