Why might inflation have occurred at the end of the GUT era? ...

[MirandaLo]

Why might inflation have occurred at the end of the GUT era?
 
  A) Gravity was an extremely weak force at this period in time.
  B) Large amounts of matter and antimatter annihilated at this time.
  C) There wasn't enough matter present to slow down the expansion at that time.
  D) The universe was too small and needed to grow quickly.
  E) An enormous amount of energy was released when the strong force froze out from the GUT force.

Question 2

The crossover point from radiation to matter domination occurred
 
  A) when the strong force separated from the other two forces.
  B) with the emission of the cosmic background radiation.
  C) about 50,000 years after the Big Bang, at a temperature of about 16,000 K.
  D) with the creation of neutrons and protons, at about 1013 K.
  E) with the creation of electrons and positrons at about 6  109 K.

[Brummell1998]

Answer to Question 1

E

Answer to Question 2

C