The table below shows the half-life of an element Half-Life Data Element Half-Life Uranium-235 700 million years Scientists have found that the uranium-235 content of an unknown prehistoric sample was reduced to one-half. What best describes the identity of the sample? O A rock that formed 700 million years ago O A rock that formed 1,400 million years ago An organism that died 700 million years ago An organism that died 1,400 million years ago