A. 240
B. 120
C. 60
D. 180
🧠 Explanation:
Red blood cells (RBCs) have an average lifespan of about 120 days in the human body. They are produced in the bone marrow and circulate through the bloodstream, carrying oxygen to tissues and removing carbon dioxide. After about four months, old RBCs are broken down in the spleen and liver. The iron from hemoglobin is recycled for new cell production. This continuous cycle ensures efficient oxygen supply, making RBC lifespan a vital factor in human health.
