Answer:
The X components of Dev's blood, which increase significantly with infectious disease, are leukocytes.
Step-by-step explanation:
Leukocytes, also called white blood cells, are the cellular components of the blood that are responsible for the body's defenses and protection.
When a pathogen —usually a bacterium— enters the body, an infectious disease occurs. In response to an infection, white blood cells increase in number in order to fight the infection.
This is why the X component of Dev's blood, leukocytes, increases significantly when Dev has an infectious disease.