This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Confounding and Bias, Subject name: Social & Preventive Medicine
[{'content': 'In a double blind clinical drug trial - \nSelect and explain. \nA. Each patient receives a placebo, B. Each patient receives both (double) treatment, C. The patients do not know which treatment they are receiving, D. The patients do not know that they are in a drug trial', 'role': 'user'}, {'content': "Answer: C \nExplanation: DOUBLE BLINDING: In a double-blind trial, the patients as well as the investigator are blinded i.e. they don't know who is receiving the study drug and who is receiving placebo. It removes subject & investigator bias. MC binding seen. OTHER TYPES OF BLINDING: Single blinding : Subjects are not aware of treatment. Used to remove subject bias. Triple binding : Subject, investigator & analyzer are not aware of treatment. Removes subject, investigator & analyzer bias. It is best blinding. Open study : Complete absence of blinding.", 'role': 'assistant'}]