Final answer:
An endemic disease (option B) is one that is constantly present in a population, typically at a low incidence, as opposed to epidemics or pandemics that affect a large number of people either locally or globally.
Step-by-step explanation:
A disease that normally occurs continuously at a relatively stable rate within a given population or geographic area is considered an endemic disease. Unlike epidemic diseases, which occur in an unusually high number of individuals within a population at the same time, endemic diseases are usually present at a low consistent incidence. For instance, malaria is endemic in certain tropical countries, meaning it's transmitted year-round rather than in periodic outbreaks. In contrast, a pandemic is a widespread, often worldwide epidemic, affecting an exceptionally high proportion of the global population.