blood is made up of blood cells & blood is a vehicle for carrying oxygen from the lungs to the rest of the body ->  blood cells carry oxygen to the body  red blood cells contain hemoglobin & red blood cells are a kind of blood cell ->  red blood cells are a kind of blood cell that contain hemoglobin  red blood cells are a kind of blood cell that contain hemoglobin & hemoglobin is a kind of protein that carries oxygen ->  red blood cells are a kind of blood cell that contain a protein that carries oxygen  blood cells carry oxygen to the body & red blood cells are a kind of blood cell that contain a protein that carries oxygen -> red blood cells carry oxygen throughout the body