Put the following steps that occurred in the first few seconds of the early Universe into chronological order:
A. e⁻ and e⁺ annhilate, limiting the number of e− available for inverse beta decay
B. The baryonic matter content of the Universe settles at a mass ratio of 25% He to 75% H.
C. The relative number of free neutrons and protons is constant because kT is much larger than the mass difference × c²
D. Deuterium begins to form, locking up free neutrons in nuclei
E. The neutron-to-proton ratio declines to ∼1/7 due to the decay of free neutrons
