In a two-by-two table, which cell denotes Unexposed and No Disease?

• A. d
• B. a
• C. b
• D. c

Answer: (A)

In a 2x2 table for epidemiology, you have exposure status on one axis (Exposed vs Unexposed) and disease status on the other axis (Disease vs No Disease). Each cell represents a specific combination of those two factors. The bottom-right cell corresponds to people who were not exposed and do not have the disease. That’s why this position denotes Unexposed and No Disease.

So, the correct choice is the one that maps to that bottom-right position. The other cells would be Exposed with Disease (top-left), Exposed without Disease (top-right), and Unexposed with Disease (bottom-left).