Type of bacteria that is completely harmless and do not cause disease.

• A. Pathogenic
• B. Nonpathogenic
• C. Opportunistic
• D. Beneficial

Answer: (B)

Nonpathogenic bacteria are those that do not cause disease in healthy hosts. They can be part of normal skin or environmental flora and may even play beneficial roles, such as supporting harmless microbial balance. Pathogenic bacteria have the ability to cause illness. Opportunistic bacteria typically don’t cause disease unless a person's immune system is weakened or they enter areas where they don’t belong. Beneficial bacteria provide positive effects but aren’t defined by being strictly harmless in all situations; the key idea here is that nonpathogenic bacteria do not cause disease under normal conditions.