Each of the following is a use of radiographs in the assessment of periodontal disease prognosis EXCEPT one. Which one is the EXCEPTION?

a. Evaluating root-to-crown ratio
b. Detecting furcation involvement
c. Determining active versus inactive disease
d. Revealing root shape and length

c. A complete periodontal assessment must include a clinical examination. Because radiographs cannot image the condition of soft tissues, a clinical examination must be used to distinguish between active and inactive disease.