Answer:
Chronic hepatitis patients.
Explanation:
Susceptibility is in medicine a characteristic of a living organism that determines its ability to become ill when in contact with infectious agents.
Susceptibility can also be called a property of a particular strain of bacteria, a population of parasites or viruses. Susceptible organisms are those that die and / or slow down reproduction under the influence of the considered effect (for example, biochemical, in the form of an antibiotic, or physical, in the form of a certain temperature).
The best answer to fill in the blank would be ''Bystander'' because as that role you can go tell any adult or higher authority to stop the fighting so you don't try to be a hero and get yourself hurt as well.
