Which statement describes a pathogenic microorganism?

• A. Are harmless to humans
• B. Produce or are capable of producing diseases
• C. Do not cause disease
• D. Are always noninfectious

Answer: (B)

Pathogenic microorganisms are defined by their ability to cause disease in a host. They can invade tissues, disrupt normal functions, or release toxins that lead to illness, so the statement that a pathogen produces or is capable of producing diseases best describes a pathogenic microorganism. The other descriptions—being harmless, not causing disease, or always being noninfectious—do not fit because many pathogens are infectious and can spread, causing illness in susceptible individuals.