The author implies that ______.
A.it is sometimes easier to detect supernovas by observation of the X-ray spectrum than by observation of visible wavelengths of light
B.life on the earth is endangered by its constant exposure to radiation forces that are released by a supernova
C.recently discovered meteorites indicate that the earth and other planets of our solar system survived the explosion of a supernova several billion years ago
D.lighter elements are formed from heavier elements during a supernova as the heavier elements are torn apart