The term 'transboundary' refers to a disease that has the potential for very rapid spread irrespective of national borders. This statement describes:

• A. A disease confined to a single country
• B. A disease that is hereditary
• C. A disease that has the potential for rapid spread across borders regardless of nationality
• D. A disease caused by toxins

Answer: (C)

Transboundary describes diseases that move beyond political borders quickly, driven by the movement of people, animals, and goods, as well as ecological connections. The key idea is that borders don’t stop the spread, so a disease with potential for rapid cross-border transmission fits this term. The statement emphasizes rapid spread across borders regardless of nationality, which matches that concept exactly. This isn’t about being hereditary (genetic transmission) or about toxins causing disease; those describe different mechanisms, not the international spread pattern.