A pandemic is a large-scale epidemic that occurs when a disease emerges for which there is little or no immunity in the human population

• A. Endemic disease
• B. Epidemic confined to one region
• C. Pandemic
• D. Seasonal illness

Answer: (C)

A large-scale outbreak across multiple regions or countries, caused by a pathogen for which little or no immunity exists in the human population, is what defines a pandemic. When a disease spreads widely and rapidly beyond local areas, populations around the world face heightened risk because few people have prior immunity to that new threat, making containment more challenging and requiring global public health coordination.

Endemic disease describes something regularly found in a particular area, with a relatively stable level of cases over time, not a new, widespread outbreak. An epidemic confined to one region is a spike in cases that remains geographically limited, so it doesn’t meet the global scope of a pandemic. A seasonal illness occurs at predictable times each year due to seasonal factors and patterns, not because of a new, globally spreading pathogen with little existing immunity.

That combination of broad geographic spread and low population immunity is why the best answer is pandemic.