The Planck Era Refers to the

Multiple Choice

The Planck era refers to the

A) time at which the expanding universe became transparent to radiation.
B) time of extremely rapid inflation that started 10^-35 s after the universe began.
C) first 10^-43 s of time, when all four fundamental forces are believed to have been united.
D) present age of the universe as given by the Hubble law.