A Systematic Review Should Address the Components Specified in PICOS

A systematic review should address the components specified in PICOS. Why is this so?

A) Interventional research always uses some means of comparison.
B) "Interventions" that are actually naturally occurring conditions should be noted, since they decrease confirmatory power of the collective evidence.
C) Study design is essential, since recommendations for change in practice can be based only on some designs.
D) Desired outcomes, not actual outcomes of the study, are the focus of the review.
E) The specific population from which a sample was drawn, and its similarity to those of others studies reviewed, affects generalizability.