Which measure is used to describe the frequency of new cases of a disease in a population?

Correct Answer: B

Rationale: Incidence (B) measures new cases over a period, reflecting disease onset. Prevalence (A) is total cases, morbidity (C) is disease burden broadly, and mortality (D) is deaths, not new cases.

Correct Answer: C

Rationale: Primary prevention (C) prevents disease onset via education/promotion (e.g., vaccination). A is secondary, B is tertiary, D is monitoring.

Correct Answer: D

Rationale: Attrition bias (D) arises from differential loss to follow-up affecting results (e.g., in cohorts). A is selection, B is data error, C is recall.

Correct Answer: B

Rationale: Descriptive studies (B) describe disease patterns (e.g., who, where, when). A and C are analytical, D is clinical.

Correct Answer: B

Rationale: Matching (B) reduces confounding (e.g., age-matching) in case-control studies. A, C, and D are incorrect or unrelated.