Final answer:
The question pertains to the synthesis of findings from multiple randomized controlled trials. The correct methodology for this is a meta-analysis, which is a powerful tool in experimental research combining data from RCTs to form robust conclusions.
Step-by-step explanation:
The question addresses the type of methodology used in medical research, specifically within the context of a systematic review of all relevant randomized controlled trials (RCTs). The correct answer to the question is meta-analysis. This research method involves the synthesis of data from multiple studies to arrive at a comprehensive understanding of a particular topic or treatment efficacy. RCTs are considered the gold standard in experimental research because they use randomization to assign participants to either the treatment or control group, thereby minimizing biases. A systematic review of RCTs often culminates in a meta-analysis, which aggregates the findings from individual studies to strengthen the power and validity of the conclusions drawn.
While other observational study types mentioned, such as cross-sectional studies, have their place in research, they are not as robust as RCTs in determining causality. This highlights the importance of carefully selecting the research method that best fits the study objectives.