The correct answer is option 2: around 120 days. Red blood cells, also known as erythrocytes, have an average lifespan of approximately 120 days in the human body. They are constantly being produced in the bone marrow to replace old or damaged red blood cells. This process is necessary to maintain the body`s oxygen-carrying capacity. After their lifespan, red blood cells are broken down and removed by the spleen and liver. While it is true that red blood cells do not live as long as humans, it is important to note that the lifespan of red blood cells varies slightly from person to person. Generally, the average lifespan of red blood cells is considered to be around 120 days.