Respuesta :
Placebo-controlled studies is one of the ways testing a medical research in which, in addition to a group of subjects that receives the treatment to be evaluated, a separate control group receives a sham "placebo" treatment which is specifically designed to have no real effect. So, the answer for this question is letter D. Those placebo doses are for used as a control group in an experiment.
Answer: D. for use on a control group in an experiment.
Explanation:
A control group is the group in an experimental study that does not receive any treatment like other variables used in an experiment. It is used as a benchmark or standard of the experiment for comparing the change occurring in other variables.
As it is mentioned that a number of placebos are prepared and has no medical effects then it is can be used as a controlled group of the experiment.