Q: Where are most white blood cells made?


Read this paragraph and choose the correct option from the provided answers:

White blood cells (WBCs) are usually larger than red blood cells. They do not have hemoglobin and do not carry oxygen. White blood cells make up less than one percent of the blood's volume. Most WBCs are made in the bone marrow, and some mature in the lymphatic system. There are different WBCs with different jobs. WBCs defend the body against infection by bacteria, viruses, and other pathogens . WBCs do have a nucleus and other organelles.

 Choices:

- lungs

- heart tissue

- plasma

- the bone marrow


A:
the bone marrow