A researcher has limited time and funds. Which research design would be most appropriate?

Correct Answer: D

Rationale: Because longitudinal, cohort, or incidence studies are costly in terms of resources and staff and often lose subjects over time, a retrospective study may be used because it is faster and less demanding of resources.

Correct Answer: C

Rationale: The epidemiological triad is host (A), agent (B), and environment (C). Pathogen (D) is a type of agent, not a separate component.

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: Information bias (B) includes misclassification influenced by outcome knowledge (e.g., recall bias in cases). A is selection, C is specific recall, D is confounding.

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.