8. The widely accepted big bang theory holds that the universe began in an explosive instant ten to twenty billion years ago and has been expanding ever since. (A) that the universe began in an explosive instant ten to twenty billion years ago and has been expanding (B) that the universe had begun in an explosive instant ten to twenty billion years ago and had been expanding (C) that the beginning of the universe was an explosive instant ten to twenty billion years ago that has expanded (D) the beginning of the universe to have been an explosive instant ten to twenty billion years ago that is expanding (E) the universe to have begun in an explosive instant ten to twenty billion years ago and has been expanding