What Do We Mean by Inflation

What do we mean by inflation?

A) A sudden and extremely rapid expansion of the universe that occurred in a tiny fraction of a second during the universe's first second of existence
B) The expansion of the universe that we still observe today
C) The sudden release of photons when a particle and antiparticle annihilate one another
D) Quantum fluctuations by high speed, relativistic particles in a state of false vacuum that caused disturbances in the space-time continuum leading to the process described in the question to which this answer refers