Correct Answer: C — Systematic Review and Meta-Analysis of RCTs

Hierarchy of Evidence (Oxford Levels):

Level	Evidence Type	Strength
I	Systematic Reviews / Meta-Analyses of RCTs	Strongest
II	Individual RCTs	Strong
III	Controlled trials without randomization	Moderate
IV	Cohort / Case-control studies	Moderate-weak
V	Systematic reviews of descriptive studies	Weak
VI	Single descriptive or qualitative studies	Very weak
VII	Expert opinion / Authority	Weakest

Meta-analyses pool data from multiple RCTs, giving greater statistical power and reducing random error.