Final answer:
Red blood cells, platelets, and most white blood cells are produced in the red bone marrow through the process of hematopoiesis.
Step-by-step explanation:
The part of the bone where red blood cells, platelets, and most white blood cells are produced is called the red bone marrow. This marrow is where hematopoiesis, the production of blood cells, takes place. In adults, red marrow is primarily found in the pelvis, ribs, vertebrae, and the ends of long bones like the femur and humerus. As the site of hematopoiesis, red bone marrow synthesizes billions of blood cells every day, which is crucial since the lifespan of these formed elements is often just a few hours to a few weeks.