What Do We Mean by Inflation

What do we mean by inflation?

A) the photons released when electrons and protons first combined, forming the Cosmic Microwave Background Radiation
B) the sudden release of photons when particles and antiparticles annihilate each other
C) the expansion of universe starting with the instant after the Big Bang
D) a sudden expansion of the universe driven by the energy released when the strong and electroweak forces froze out from the GUT force
E) the rapid expansion of the universe, driven by white dwarf supernova, that we still observe today