Sara has a wart on her hand. Her doctor advises her to always keep it covered to avoid spreading it to others. Which link of the chain of infection is being broken by her keeping the wart covered?

• A. Portal of entry.
• B. Mode of transmission.
• C. Portal of exit.
• D. Reservoir.

Answer: (B)

Verified step by step guidance

1. Understand the 'chain of infection,' which consists of six links: infectious agent, reservoir, portal of exit, mode of transmission, portal of entry, and susceptible host.
2. Identify that a wart is caused by a virus, which acts as the infectious agent, and the wart itself can serve as a reservoir where the virus lives.
3. Recognize that covering the wart prevents the virus from leaving the reservoir and being transferred to others, which interrupts the 'mode of transmission' link.
4. Note that 'portal of exit' refers to the path the infectious agent leaves the reservoir, but covering the wart specifically blocks transmission rather than the exit point itself.
5. Conclude that by keeping the wart covered, Sara is breaking the 'mode of transmission' link, preventing the virus from spreading to others.