Answer: Concealment of a particular group from one or more individuals
Step-by-step explanation:
Blinding is a term used to conceal a particular group from one or more individuals who are involved a clinical study. Blinding is used in this study to evaluate the placebos. This was important in this study because the treatment being done by Ā echinacea was no being effective. So in order to gain good results and to see the actual results, blinding was done.