What is the primary objective of screening in epidemiology?

Correct Answer: B

Rationale: Screening (B) detects asymptomatic cases (e.g., mammography) for early intervention. A follows detection, C and D are diagnostic/prognostic.

Correct Answer: B

Rationale: Case-control studies (B) suit rare diseases (e.g., cancer) by starting with cases. A is better for common outcomes, C for prevalence, D for trials.

Correct Answer: C

Rationale: Case-control studies use odds ratio (C) to measure association (e.g., odds of exposure in cases vs. controls). A and D are cohort measures, B is cross-sectional.

Correct Answer: C

Rationale: Cross-sectional studies (C) are quick and cost-effective (e.g., prevalence surveys). A, B, and D are false.

Correct Answer: B

Rationale: Prospective cohorts (B) track incidence and temporality (e.g., exposure before disease). A, C, and D are false.