Final answer:
An epidemic occurs when a specific disease affects a large number of people in a population at the same time. The correct answer is option 4.
Step-by-step explanation:
An epidemic occurs when there is a disease that occurs in an unusually high number of individuals in a population at the same time. Therefore, the correct answer to the question is option 4) a large number of people get a specific disease. Epidemiologists are the scientists who study how diseases affect a population, and a disease that shows up to a lesser extent on a regular basis is known as an endemic disease. When an epidemic spreads across multiple populations or globally, we refer to it as a pandemic.