Answer:
The given blank can be filled with antigens.
Step-by-step explanation:
The immune system safeguards the body from probable harmful components by identifying and reacting towards the antigens. The antigens are the components generally the proteins found on the surface of the viruses, cells, or bacteria.
The non-living components like the chemicals, drugs, toxins, and foreign substances like splinter can also be the antigens. The immune system identifies and eradicates, or attempts to destroy the components, which comprise antigens.