Which of the following is a Bradford Hill criterion for causality?

• A. Randomization
• B. Dose-response relationship
• C. Specificity
• D. Coherence

Answer: (D)

In epidemiology, several criteria help judge whether an observed association could be causal, and one of them is coherence. Coherence means the proposed cause-and-effect relationship should fit with what we already know about the biology, pathophysiology, and natural history of the disease. If the association implies biology that makes no sense given current scientific understanding, the causal interpretation is questioned, even if there’s an association.

Why this choice is the best here: coherence emphasizes compatibility with existing knowledge, which helps ensure that a causal claim isn’t just a statistical coincidence but a story that makes biological sense. Other options relate to study design or patterns of association (randomization is a method to reduce bias; dose–response and specificity are other Bradford Hill considerations), but they don’t capture the idea of being consistent with established biology as clearly as coherence does.