Hemocytoblast cells
a. are abundant in the plasma.
b. are specialized cells.
c. are found in yellow bone marrow.
d. give rise to formed elements in the blood.

I believe the correct answer would be D. Hemocytoblast cells give  rise to formed elements in the blood. These cells are stem cells for elements that are blood-cellular. They are obtained from the mesoderm and are located in the bone marrow. When these cells are divided into two cells, one of the daughter cells would be come a blood cell while the other will remain as a hemocytoblast to ensure that there is enough of this cell that is available. They are considered to be able to produce all blood cell types namely white blood cells, platelets and red blood cells. To do this, they undergo the process of haematopoiesis. 

The awnser is b i believe