Based on the Observed Amount of Deuterium in the Universe

Based on the observed amount of deuterium in the universe, we can conclude that

A) the density of ordinary (baryonic) matter is about 5 percent of the critical density.
B) neutrons outnumber protons 7 to 1 in the universe.
C) we live in a critical- density universe.
D) ordinary (baryonic) matter makes 75 percent of the mass of the universe.
E) most of the deuterium that was created during the era of nucleosynthesis has since been destroyed.