Final answer:
Participants in the study were given placebos, which are substances without a therapeutic effect, used to control for the placebo effect in clinical trials.
Step-by-step explanation:
The tonics described as being administered in the hospital are actually placebos, which are not real medications but substances that have no therapeutic effect. A placebo is a "fake" treatment included in a study to control for the placebo effect, which is a psychologically based reaction to a treatment that occurs just because the subject is treated, even if the treatment has no physiological effect on health. The correct answer to what participants in the study were given is placebos.
The use of placebos has a historical context as well. History has shown various instances where pseudoscientists and tonic peddlers offered medicinal potions that were claimed to solve health problems but often contained harmful ingredients. In contrast, placebos are used in modern clinical trials to test the efficacy of new treatments by comparing the reaction of subjects receiving the actual treatment versus those receiving the placebo.