Which statement reflects the Germ Theory?

• A. Evolution explains species adaptation
• B. Cells are the basic units of life
• C. Matter cannot be created or destroyed
• D. Pathogens cause disease

Answer: (D)

Microorganisms cause disease. Germ Theory holds that tiny organisms—bacteria, viruses, and other pathogens—are responsible for many illnesses, and that infections can spread from person to person or through contaminated environments. This idea explains why practices like sterilization, hygiene, vaccines, and antibiotics reduce disease, and it’s supported by classic experiments showing that growth occurs only when microbes are introduced and that specific microbes are linked to particular diseases.

Other statements point to different fundamental ideas: evolution explains how species change over time, cells are the basic units of life describes cell theory, and matter cannot be created or destroyed is the conservation principle. Those are important concepts too, but they don’t describe what causes disease.