Which of the Following Has the Levels of Evidence in the Correct

Multiple Choice

Which of the following has the levels of evidence in the correct order for the hierarchy of evidence pyramid (top to bottom) ?

A) Expert opinion, case series, observational study, randomized controlled trial.
B) Observational study, non-randomized controlled trial, randomized controlled trial, systematic review.
C) Randomized controlled trial, non-randomized controlled trial, observational study, case series.
D) Systematic review randomized controlled trial, observational study, and expert opinion.