Which sentence correctly describes the difference between incidence and prevalence?

Incidence measures all cases that ever existed in history, and prevalence measures only cases that will occur in the future.

Incidence measures new cases over a specified time among those at risk, while prevalence measures all existing cases (new and preexisting) at a particular point or period in the population.

Incidence and prevalence are synonyms and can be used interchangeably to mean any count of disease regardless of time or population at risk.

Prevalence describes only severe cases while incidence reports only asymptomatic infections; the two are unrelated temporal measures.