Prevalence rate includes –

Correct option is B

Sol. Prevalence rate measures the total number of cases (both new and old) of a disease in a population at a given time. It helps in understanding the overall disease burden in a community.
Explanation of Options:
· (a) Recovered case of disease: Incorrect; prevalence includes both active and old cases.
· (b) New and old cases of disease: Correct answer; prevalence considers both types of cases.
· (c) Population at risk: Incorrect; incidence rate focuses more on at-risk populations.
· (d) New cases of disease: Incorrect; this defines incidence, not prevalence.