Question ID:PT43 S3 Q13 Passage:Up until about 2 billion years ago, the sun was 30 percent dimmer than it is now. If the sun were that dim now, our oceans would be completely frozen. According to fossil evidence, however, life and liquid water were both present as early as 3.8 billion years ago. Stem:Which one of the following, if true, most helps to resolve the apparent discrepancy described above? Correct Answer Choice:AChoice A:Our atmosphere currently holds in significantly less heat than it did 3.8 billion years ago. Choice B:The liquid water present 3.8 billion years ago later froze, only to melt again about 2 billion years ago. Choice C:A significant source of heat other than the sun contributed to the melting of ice sheets approximately 2 billion years ago. Choice D:Evidence suggests that certain regions of ocean remained frozen until much more recently than 2 billion years ago. Choice E:When large portions of the globe are ice-covered, more of the sun's heat is reflected and not absorbed by the earth than when only the poles are ice-covered.