Jane (SLP) Heard About a New Intervention Approach for Children

Jane (SLP) heard about a new intervention approach for children with a speech sound disorder at a conference but questioned the credibility of the evidence because:

A) the findings from the study were from a large randomized controlled trial.
B) the recommendation to use the approach was based on expert opinion.
C) the findings were based on a meta-analysis of six randomized controlled trials.
D) the findings were based on a series of nine quasi-experimental group investigations.