Pathogenic bacteria are bacteria that ...

• A. Cause disease
• B. Do not cause disease
• C. Are always beneficial
• D. Are viruses

Answer: (A)

Pathogenic describes bacteria that can cause disease. These bacteria have factors that let them invade tissues, damage cells, or produce toxins, leading to illness. So the statement that pathogenic bacteria cause disease is correct. Some bacteria are harmless or beneficial, which is why simply saying they do not cause disease wouldn’t capture the meaning of pathogenic. They are not viruses; bacteria and viruses are different kinds of organisms, and pathogenicity in this context refers to disease-causing bacteria, not viral pathogens.