Answer:
D
Explanation:
Bone marrow contains stems cells which then turn into immature blood cells and they mature there. kinda like a school for young blood cells. they also make white blood cells and platelets.
The nucleus directs all activities that happen within the cell and contains the cell genetic material (DNA).<span> The nucleus gives the signal to the cell to grow, divide and/or make proteins. </span>
<span>There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and the tissues; and the veins, which carry blood from the capillaries back toward the heart</span>
