When we say that the electromagnetic and weak forces "freeze out" from the electroweak force at 10-10 seconds after the Big Bang, we mean that ...
Answer
A) these forces are important only at temperatures below the freezing point of water a temperature that the universe reached at an age of about 10-10 second.
B) "freezing out" was a term coined by particle physicists who think that the Big Bang theory is really cool.
C) prior to this time the electromagnetic and weak forces maintained a single identity, but they possessed separate identities following this time.
D) following this time neither the electromagnetic nor the weak force was ever important in the universe again.
E) quantum fluctuations by high-speed, relativistic particles in a state of false vacuum cause disturbances in the spacetime continuum, leading to the process described in the question this answer refers to.