Which statement best describes quantal responses?

• A. They measure magnitude of response in individuals
• B. They describe the percentage of population that responds as dose increases
• C. They are always reversible
• D. They are the same as graded responses

Answer: (B)

Quantal responses are all-or-none outcomes observed across a population. At each dose, individuals are classified as having the predefined effect or not, and the result is expressed as the percentage of the population that responds. This population-based curve rises with increasing dose and is used to derive measures like the ED50.

This differs from graded responses, which describe the magnitude of effect within an individual on a continuous scale. Reversibility isn’t a defining feature of quantal responses, and quantal data are not the same as graded data.