This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
While assessing the efficacy of a newly developed drug in comparison to placebo, the 95% confidence interval in clinical trials is used to check for: 
Select and explain. 
A. Efficacy of the drug, B. Non-efficacy of the drug, C. Both efficacy and non-efficacy of the drug, D. Either efficacy or non-efficacy of the drug
A: Efficacy of the drug
Answer: A: Efficacy of the drug 
Explanation: Answer- a (efficacy of the drug)