Which of the following is an example of passive surveillance?

Correct Answer: A

Rationale: Passive surveillance (A) relies on routine reporting (e.g., by providers). B, C, and D are active methods requiring outreach.

Correct Answer: C

Rationale: Cross-sectional studies (C) measure prevalence at a point in time (e.g., hypertension rates). A and B focus on associations, D on interventions.

Correct Answer: B

Rationale: Cohort studies (B) track multiple outcomes (e.g., smoking and various diseases). A, C, and D are false; they’re costly, slow, and bias-prone.

Correct Answer: B

Rationale: Case-control studies (B) efficiently study rare diseases (e.g., cancer) by starting with cases. A, C, and D are false.

Correct Answer: C

Rationale: Cohort studies (C) compare exposed vs. unexposed outcomes (e.g., smoking and cancer). A is snapshot, B is retrospective, D is experimental.