What makes dark energy "dark"?
A. its unknown nature
B. its completely black color
C. its existence beyond the visible spectrum
D. its inevitable creation of a totally destructive Big Crunch

Nucleosynthesis began when _____ and ended when _____.
A. the Big Bang occurred; the Big Crunch occurred
B. nuclear reactions could first occur; matter had condensed into galaxies and stars
C. the cosmic microwave background radiation formed; dark energy replaced it as the dominant energy form
D. the universe had cooled enough for atoms to combine; protons and neutrons were too far apart to form nuclei