Which of the following statements correctly contrasts experimental clinical trials with observational studies in nutrition?

Clinical trials manipulate exposure through random assignment and can support causal inference, while observational studies only observe naturally occurring exposures and generally show associations, not causation

Observational studies always provide stronger causal evidence than randomized trials because they reflect real-world behavior without researcher interference

Clinical trials and observational studies are identical; both randomly assign exposures and therefore both equally demonstrate causation

Clinical trials are used only in laboratory animals and cannot be applied to human nutritional questions, whereas observational studies are the only human-friendly approach