The primary, natural habitat of a pathogen where it continues to exist is called the _____.

• A. carrier
• B. reservoir
• C. host
• D. vector

Answer: (B)

Verified step by step guidance

1. Understand the key terms: A 'pathogen' is a microorganism that can cause disease. The question asks about the natural place where a pathogen lives and continues to exist.
2. Define 'reservoir': In microbiology, a reservoir is the natural habitat of a pathogen where it normally lives, grows, and multiplies. This can be an organism, environment, or surface.
3. Consider other options: A 'host' is an organism that harbors the pathogen and may show disease symptoms. A 'carrier' is a host that harbors the pathogen without showing symptoms but can transmit it. A 'vector' is an organism that transmits the pathogen from one host to another.
4. Compare definitions: Since the question asks for the primary, natural habitat where the pathogen continues to exist (not necessarily causing disease or transmitting), the term 'reservoir' fits best.
5. Conclude that the correct term to fill in the blank is 'reservoir' because it specifically refers to the natural environment or organism where the pathogen is maintained.