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
Not a feature of systematic review 
Select and explain. 
A. Meta analysis is always performed, B. Search for literature is compulsory using explicit search strategy, C. Critical appraisal is always criteria based, D. Research questions always focussed
A: Meta analysis is always performed
Answer: A: Meta analysis is always performed 
Explanation: A systematic review answers a defined research question by collecting and summarising all empirical evidence that fits pre-specified eligibility criteria. A meta-analysis is the use of statistical methods to summarise the results of these studies.