If records showed that over the past thirty years the one-year cumulative incidence of a disease was stable, but the point prevalence appeared to be increasing, which of the following statements, would be the best explanation?

Select one:

a. The duration of disease is becoming shorter.

b. The case-fatality rate of this disease is increasing.

c. Treatment (but not cure) for the disease is improving

d. Efforts to prevent new cases of this disease are becoming more successful

e. The risk of the disease has decreased over the past 30 years.