Explanation:

- The Heart is essential for circulating blood but does not manufacture red blood cells. It pumps oxygenated and deoxygenated blood through the body's circulatory system.

- The Brain functions as the control center for the nervous system and is not involved in blood cell production.

- The Lungs are critical for gas exchange, especially oxygen and carbon dioxide, but do not play a role in creating red blood cells.

- Bone marrow is responsible for the production of red blood cells. It is a spongy tissue found in the center of certain bones and is the primary site for new blood cell production.

- Correct Answer: Bone marrow