Use the following information to answer the following question: you wake up one morning feeling slightly under the weather. a close family member enthusiastically suggests that you take some echinacea, an herb commonly used as a cold remedy. you then decide to design an experiment to test echinacea and see if this claim is true. you think, "if taken at the beginning of a cold, echinacea will reduce cold symptoms." you decide to test the effects of echinacea on 100 people who are experiencing similar cold symptoms. which of the following groups would represent an appropriate control in your experiment?