<span>a. a substance that is naturally found in the brain</span>
Normally, people produce about 100 billion white blood cells a day. ... However, an increase in the number of white blood cells is also caused by cancers of the bone marrow (such as leukemia) or by the release of immature or abnormal white blood cells from the bone marrow into the blood.
Overview of White Blood Cell Disorders - The Merck Manuals
https://www.merckmanuals.com/.../blood-disorders/white-blood-cell-disorders/overview-...
It is the sun. You start with photosynthesis.
