Final answer:
Washing hands frequently is the most important measure related to the susceptible host when breaking the chain of infection.
Step-by-step explanation:
The measure that would be most important related to the susceptible host when performing measures to break the chain of infection is washing hands frequently. Washing hands is a crucial practice to prevent the spread of contagious illnesses because it helps remove microbes that can make a person sick. By washing hands, the susceptible host can reduce the risk of transmitting pathogens from surfaces touched to their mouth, nose, or eyes.