Disease-causing viruses that can spread through water, air, or body fluids.

• A. Bacterial pathogens
• B. Viral pathogens
• C. Parasitic pathogens
• D. Fungal pathogens

Answer: (B)

Viruses are infectious agents that can spread through multiple routes, including water, air, and contact with body fluids. This combination of transmission modes is a hallmark of many viral diseases: waterborne viruses such as norovirus or hepatitis A contaminate drinking water or foods; airborne viruses like influenza or measles travel through respiratory droplets in the air; and viruses such as HIV or hepatitis B transmit through infected body fluids. Bacteria, parasites, and fungi can also spread via water or air, or through fluids, but the specific pattern described—a disease-causing agent that commonly moves through water, air, and body fluids—points to viruses as the category.