Which word describes marrow that produces red blood cells?

• A. Red marrow
• B. Yellow marrow
• C. Fat marrow
• D. Dense marrow

Answer: (A)

Red marrow is the tissue in bones where blood cells are formed, a process called hematopoiesis. It contains the developing red blood cells (along with white cells and platelets) and is richly supplied with blood vessels to support this production. Because of its role, red marrow is where red blood cells originate and mature. Yellow marrow, by contrast, stores fat and does not actively produce blood cells under normal conditions, which is why it isn’t the term used to describe marrow that makes red blood cells. Dense marrow isn’t a standard description for marrow type. So, the word that describes marrow producing red blood cells is red marrow.