Which of the following describes a decrease in the number of disease cases over time?

The term that accurately describes a decrease in the number of disease cases over time is "decline." When discussing diseases in a population over a specified period, a decline indicates a reduction in the frequency of cases, which can result from effective public health interventions, disease control measures, or natural trends in disease occurrence.

To provide additional context, prevalence refers to the total number of existing cases of a disease in a population at a specific point in time, rather than focusing on changes over time. Incidence, on the other hand, measures the number of new cases that occur in a population during a specific time frame, which does not directly reflect a decrease in disease cases. Remission typically refers to a period during which symptoms of a disease lessen or disappear, often in the context of chronic conditions rather than a broader decrease in case numbers.

Thus, the choice "decline" clearly captures the concept of a reduction in disease cases over time, making it the correct answer.