Which of the following statements is true?

A. Primordial nucleosynthesis did not take place during the first three minutes of the universe because the temperature of the universe was sufficiently high to immediately dissociate any deuterium formed.
B. Once the temperature of the universe dropped below 9 × 108 K, protons and neutrons fused, forming deuterium, and deuterium then fused with other particles, forming primarily helium.
C. Primordial nucleosynthesis ended when the density and temperature of the universe dropped too low for fusion to continue.
D. Primordial nucleosynthesis ended about 400,000 years after the Big Bang.