Which factors are necessary to assume there might be a cause-effect relationship between a particular variable A and a specific illness? (Select One that does not apply.)

Correct Answer: C

Rationale: There are six criteria for assuming possible causation including strength of the association, dose-response relationship, temporally correct relationship, biological plausibility, consistency among studies, and specificity. Only the 'easy-to-understand,' consistent research studies and the increased dose leading to increased illness are consistent with those six criteria.

Correct Answer: B

Rationale: Malaria (B) is vector-borne, transmitted by mosquitoes. Tuberculosis (A), influenza (C), and measles (D) are airborne or direct-contact diseases.

Correct Answer: B

Rationale: Epidemic (B) is excess cases beyond expected (e.g., flu outbreak). A is normal, C is global, D is occasional.

Correct Answer: A

Rationale: Natural history (A) is disease progression without intervention (e.g., HIV stages). B, C, and D are unrelated aspects.

Correct Answer: C

Rationale: Cross-sectional studies (C) can’t determine causality due to simultaneous exposure-outcome measurement. A, B, and D may apply but aren’t primary.