In adult Human R.B.C. is formed in :

Question

Accepted Answer

In adult humans, red blood cells (R.B.C.s) are primarily formed in the bone marrow, which is why Option 2 is the correct answer. The bone marrow is a spongy tissue found in the hollow centers of certain bones, such as the pelvis, femur, and sternum. It is the primary site of hematopoiesis, the process by which blood cells, including red blood cells, are produced. The bone marrow contains stem cells that differentiate into various types of blood cells, including erythrocytes (red blood cells), which are essential for carrying oxygen throughout the body.

Now, let's examine why the other options are incorrect:

1. **Liver (Option 1):** While the liver plays a crucial role in various metabolic processes and the breakdown of old red blood cells, it is not the primary site for the formation of new red blood cells in adults. During fetal development, the liver does contribute to blood cell formation, but this function is taken over by the bone marrow after birth.

3. **Kidney (Option 3):** The kidneys are involved in the regulation of red blood cell production through the secretion of erythropoietin, a hormone that stimulates the bone marrow to produce red blood cells. However, the kidneys themselves do not form red blood cells.

4. **Pancreas (Option 4):** The pancreas is primarily involved in the production of digestive enzymes and hormones such as insulin. It does not play a role in the formation of red blood cells.

In summary, the bone marrow is the correct and primary site for red blood cell formation in adult humans, making Option 2 the correct answer.