Answer:
The correct answer is option a, that is, 3000 cases.
Step-by-step explanation:
The measurement of all the individuals getting influenced by the disease at a specific time is known as the prevalence. On the other hand, the measurement of the number of novel individuals that came into contact with a disease during a specific time duration is known as the incidence.
Based on the given question, the number of prevailing cases carried from 2018 to 2019 is 2000, and the new diseases recorded in the year 2019 is 1000 (incidence). Therefore, the prevalence of the disease in 2020 will be 3000 cases.