Respuesta :
D control, the researchers are creating a control group that experience all of the same conditions of the test group (receiving a pill) but receive no benefit of the vitamin. It helps to reduce variable in the study to determine validity
The researcher is incorporating control aspect of successful experimental design in his study.
What is control experimental design?
Control experimental design is an experiment the researcher forms or selects the groups under study, manipulates the treatments for the groups, attempts to to control extraneous or confounding variables.
For example, in this particular question, the researcher must want to study the effect of a vitamin. Therefore, he created two groups - one set of people consumed the vitamin and other set only thought that they did. The group that receives the treatment in an experiment is called the experimental group, while the group that does not receive the treatment is called the control group. The control group provides a baseline that lets us see if the treatment has an effect.
Learn more about control experimental design here
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