What type of study design is most suitable for establishing a cause-and-effect relationship?

Correct Answer: D

Rationale: Randomized controlled trials (RCTs, D) establish causality by controlling confounding through randomization and intervention. Cohort (B) and case-control (C) studies suggest associations, while cross-sectional (A) studies assess prevalence, not causation.

Correct Answer: C

Rationale: A risk factor (C) increases disease likelihood (e.g., smoking for lung cancer). A is causation, B reduces risk, D is intervention.

Correct Answer: B

Rationale: Etiology (B) is the study of disease causes (e.g., bacteria for TB). A, C, and D are consequences or responses.

Correct Answer: A

Rationale: Descriptive studies (A) generate hypotheses by observing patterns (e.g., cholera maps). B tests, C experiments, D is non-epidemiological.

Correct Answer: B

Rationale: Cohort studies (B) are observational, tracking natural exposure-outcome links. A and D are experimental, C is lab-based.