Which statement best describes the relationship between Category A and Category B Infectious Substances as presented?

• A. Category A defines fatal or life-threatening disease in otherwise healthy humans and animals, while Category B includes other infectious substances not meeting that criteria
• B. Category A and B are the same
• C. Only Category B exists
• D. Not regulated

Answer: (A)

The main idea here is how infectious substances are grouped by risk for shipping. Category A includes those infectious substances capable of causing a fatal or life-threatening disease in otherwise healthy humans or animals. Category B covers all other infectious substances that do not meet that high-risk criterion. This separation explains why Category A materials require stricter packaging, labeling, and documentation than Category B materials, since they pose a greater potential threat if released during transport. The statement described fits this relationship precisely: Category A is defined by the potential to cause severe disease, while Category B consists of infectious substances that don’t meet that high-risk threshold. The other options don’t reflect this risk-based distinction or the existence of two distinct categories.