Which of the following is explicitly identified as Category B Infectious Substance in the material?

• A. A cerebral spinal fluid sample from a patient potentially infected with EEE
• B. A blood sample with unknown medical history
• C. A throat swab culture
• D. A plant pathogen culture

Answer: (A)

Category B Infectious Substances cover diagnostic or clinical specimens that may contain infectious agents but do not meet the criteria for Category A. These materials are shipped under UN 3373 with packaging suited for diagnostic workups. The cerebral spinal fluid sample from a patient potentially infected with EEE is a human clinical specimen used to diagnose a potentially serious infection, and in the material it is explicitly identified as a Category B example. That explicit designation makes it the best choice because it aligns directly with the defined category: a diagnostic human specimen that requires appropriate but non-Category-A packaging and handling.

The other options involve different contexts: a blood sample with unknown medical history is also a human clinical specimen, but if the material doesn’t explicitly label it as Category B, it wouldn’t be the identified example. A throat swab culture and a plant pathogen culture either may not be the explicitly listed Category B example in the material, or (in the case of a plant pathogen) fall outside the scope of human clinical infectious substance classifications.