Not a feature of systematic review: (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
Answer is A. 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.