Which of the following best describes a pathogen?

• A. A cell that produces antibiotics
• B. An organism that causes disease in its host
• C. A microorganism that is beneficial to its host
• D. A non-living particle that cannot infect living organisms

Answer: (B)

Verified step by step guidance

1. Understand the term 'pathogen' in microbiology: it refers to an agent that causes disease in another organism, typically a host.
2. Review each option carefully and compare it to the definition of a pathogen.
3. Option 1 describes a cell that produces antibiotics, which is not necessarily a pathogen; antibiotics are substances that inhibit or kill other microorganisms.
4. Option 3 describes a microorganism beneficial to its host, which is the opposite of a pathogen since pathogens cause harm.
5. Option 4 describes a non-living particle that cannot infect living organisms, which excludes it from being a pathogen because pathogens must be able to infect and cause disease.