Answer:
Lungs supply oxygen carried by blood to cells of the body. The cells which are responsible for the transportation of oxygen is hemoglobin. When oxygen rich hemoglobin reaches a cell so the oxygen is unloaded and carbondioxide which is produced as a waste product is loaded in hemoglobin. Again this hemoglobin goes to the lungs and dispose carbondioxide there and repeat the process again.
To check your answer at least twice
The answer is, "B", "Sugars".
