Active bone marrow in adult human being is about
A. 3.5- 6 percent of the body weight
B. 3.5- 6 percent of total blood
C. 3.5- 6 percent of the total body fluid
D. 3.5- 6 percent of coelomic fluid

Hint: Bone marrow, like inside the hip and thigh bones, is the spongy tissue between some of the bones in the body. Immature cells, or stem cells, contain the bone marrow. The stem cells will grow into red blood cells that transport oxygen across your body, infection-fighting white blood cells, and platelets that help clot blood.

Complete answer:
Bone marrow is soft gelatinous tissue that fills the central part of the bones, the medullary cavities. Red Bone marrow, known as myeloid tissue, and yellow bone marrow, or fatty tissue, are both forms of bone marrow. A fragile, highly vascular fibrous tissue containing hematopoietic stem cells consists of the red bone marrow. These are stem cells that compose blood. There are mesenchymal stem cells, also known as marrow stromal cells, in the yellow bone marrow. These generate fat, bone, and cartilage. Bone marrow first forms in the clavicle before birth, near the end of fetal development. After about 3 weeks, it becomes active. At 32 to 36 weeks ' gestation, bone marrow takes over from the liver as the major hematopoietic organ. The largest concentration of red marrow in adults is in the bones of the vertebrae, breastbone (sternum), hips (ilium), skull, ribs, and in the long bones of the arm (humerus) and femur and tibia in the leg at the metaphysical and epiphyseal ends. Active bone marrow is 3.5- 6 percent of the bodyweight

So, the correct answer is option (A).

Note: A bone marrow transplant is a procedure that substitutes a good one for an unhealthy marrow. It is also called a transplant of blood or marrow. To kill the diseased blood-forming cells and marrow, one gets chemotherapy with or without radiation before transplantation. Then, there are healthy cells that go into the bloodstream. The cells find their way into the marrow, where they develop and begin to produce healthy red blood cells, platelets, and white blood cells.