GRE Logical Reading: ETS-GRE逻辑单题ETS - 851IBIL4XFGG4XLQK$

The early universe contained only the lightest elements, hydrogen and helium. Heavier elements, such as carbon, form only in nuclear reactions in stars and are dispersed when the stars explode. A recently discovered gas cloud contained carbon several billion years ago, when the universe was no more than two billion years old.