In an experimental study of the effects of a new drug on depression a double-blind control technique is used, which of the following persons should not be informed as to which drug, experimental or placebo is being administered to each individual research participant?<br>1. Research participants in the experimental group.<br>2. Research participants in the control group.<br>3. Persons administering the drug.<br>4. Persons evaluating the drug effect.<br>Select the correct answer:

Correct Answer: 1, 2 and 4