Answer:
-White blood cells.
Step-by-step explanation:
White blood cells (or leukocytes) represent a type of blood cells that provide protection against foreign pathogens and infectious diseases.
These cells include both non-specific immune cells (such as neutrophils and eosinophils) and specific immune cells (T and B lymphocytes). These cells kill and eliminate pathogens from the body by various mechanisms, such as phagocytosis or substances, such as cytokines and antibodies.
Thus, if a person is infected by flu virus, the blood component that helps him to attack the pathogen would white blood cells.