At what point do the weak nuclear and electromagnetic forces split?
A) never, they are still united
B) at 1012 K, when pair production starts for neutrons and protons
C) at 10-43 seconds, when all four forces separate as the Planck Era ends
D) at about four seconds, when at millions of degrees hydrogen forms helium
E) after about 10-10 seconds, when the temperature drops below 10-15 K
E
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