This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
In a double-blind clinical drug trial: 
Select and explain. 
A. Each patient receives a placebo, B. Each patient receives both (double) treatments, C. The patients do not know which treatment they are receiving, D. The patients do not know that they are in a drug trial
C: The patients do not know which treatment they are receiving
Answer: C: The patients do not know which treatment they are receiving 
Explanation: The double blind trial is so planned that neither the doctor nor the paicipant is aware of the group allocation and the treatment received. Ref: 25th edition, Park's Textbook of Preventive and Social Medicine, Page no. 91