Answer:
One group was given a sugar tablet as a placebo in order to include a control group. The correct answer is A.
Explanation:
In all these kinds of experiments with certain medicine in people's bodies, there is one group included that is given placebo -not real medicine, in this case just sugar- in order to let them feel they did actually took the real medicine and have them controlled. By doing this, they don't change their beliefs about the value of a treatment.
