They produce pockets (eggs) for fertilization and they produce the reproductive hormones, oestrogen and progesterone.
Nervous muscle action pressure
Your answer is D. untestable and open to change
Echinoderms, like chordates, are deuterostomes and are therefore thought to be the most closely related of the major phyla to the chordates
Answer:
Bone marrow.
Explanation:
Hematopiesis may be defined as the formation of the blood cells by the precursor stem cells. This process occurs in the bone marrow, thymus and liver.
The red blood cells are enucleated cells with the minimum span of around 120 days. These cells are processed and destroyed in the spleen. The iron is recovered from the red blood cells and sent again into the bone marrow for the production of new blood cells.
Thus, the answer is bone marrow.
