The correct option is B Spleen
The spleen plays important roles in regard to red blood cells and the immune system. It removes old red blood cells and holds a reserve of blood, which can be valuable in case of hemorrhagic shock, blood loss and also recycles iron. It purifies the blood and helps the immune system to recognize and attack foreign antibodies and disease. The spleen is composed of the red and white pulp. The white pulp produces and grows immune cell as well as blood cells. On the other hand, the red pulp is responsible for purifying the blood and removing dead or old blood cells.