Which statement best defines a nonpathogen microorganism?

• A. Evades the immune system
• B. Causes disease
• C. Do not pose a particular threat to health
• D. Is capable of rapid replication

Answer: (C)

Nonpathogenic microorganisms are those that do not cause disease and generally do not threaten health. They can be harmless or even beneficial, helping with processes like digestion or protecting against harmful microbes. The idea here is that they don’t pose health risks under normal circumstances, which is what makes them nonpathogenic.

Evading the immune system and causing disease are traits we associate with pathogens, which are harmful microbes. Rapid replication isn’t a defining feature of nonpathogens—some harmless microbes can replicate quickly, while others do so slowly—so it doesn’t determine whether something is nonpathogenic.