Which of the following is the most common way a pathogen enters a new reservoir?

• A. Via photosynthesis by the reservoir organism
• B. Through direct contact with an infected host
• C. By spontaneous generation within the reservoir
• D. By passive diffusion through the air without any carrier

Answer: (B)

Verified step by step guidance

1. Understand the concept of a pathogen's reservoir: a reservoir is any person, animal, plant, soil, or substance in which an infectious agent normally lives and multiplies, serving as a source from which other individuals can be infected.
2. Review the possible modes of pathogen entry into a reservoir: these include direct contact with an infected host, environmental generation, passive diffusion, or biological processes like photosynthesis (which is unrelated to pathogen entry).
3. Eliminate options that are biologically implausible: photosynthesis is a process by which plants produce energy and does not relate to pathogen entry; spontaneous generation is an outdated and disproven concept; passive diffusion through air without a carrier is unlikely to establish a pathogen in a reservoir.
4. Focus on the most common and scientifically supported mode: pathogens typically enter new reservoirs through direct contact with an infected host, allowing transfer of the infectious agent.
5. Conclude that the correct answer is 'Through direct contact with an infected host' because it aligns with established microbiological principles of pathogen transmission and reservoir colonization.