An organism that is capable of causing infection is known as a/an:

• A. Bacteria
• B. Pathogen
• C. Virus
• D. Fungus

Answer: (B)

Pathogen is the term for any organism or agent that can cause disease in a host. It covers bacteria, viruses, fungi, and parasites—essentially anything that has the potential to lead to infection. The reason this is the best choice is that it describes the capability to cause infection rather than naming a specific type of organism. While the other options (a type of organism) can be infectious, they’re not universal descriptors of anything that can cause infection. Some bacteria, viruses, or fungi may be harmless or nonpathogenic in certain contexts, but a pathogen specifically refers to the disease-causing potential.