Biological Agent is defined as which of the following?

• A. A chemical compound used as a pesticide.
• B. A microorganism, or a toxin derived from a microorganism, which causes disease in man, plants, or animals, which causes the deterioration of material.
• C. A virus designed for use in vaccines.
• D. A nonpathogenic yeast.

Answer: (B)

A biological agent is any microorganism or toxin produced by a microorganism that can cause disease in living hosts—humans, animals, or plants. This definition focuses on the potential to harm through illness, and sometimes includes effects on materials, but the essential idea is disease-causing capability from a biological source.

That description fits the option because it explicitly mentions a microorganism or a toxin derived from one with the capacity to cause disease in living beings. The other options describe a chemical pesticide, a virus designed for vaccines (which is typically engineered for safety and not intended to cause disease), or a nonpathogenic yeast (which by definition does not cause disease).