How does a randomized controlled trial compare to a cohort study in terms of bias risk and causal inference?

How does a randomized controlled trial compare to a cohort study in terms of bias risk and causal inference?

• A. Cohort studies provide stronger causal inference than RCTs.
• B. RCTs minimize confounding via randomization and provide stronger causal inference; cohort studies are observational and more prone to confounding.
• C. Both have identical bias risk.
• D. RCTs have higher bias risk than cohorts.

Answer: (D)