It produces lymphocytes, is important for T cell maturation (T for thymus-derived). The spleen is an organ in the upper left abdomen, which filters blood, disposes of worn-out red blood cells, and provides a 'reserve supply' of blood. It contains both red tissue, and white lymphatic tissue. Hope that helped!
Im 98% sure its the 3rd one... the other 2% im not that sure
Involves actual transfer of electrons