Electron Microscopy Samples Are Often Chemically Fixed Before Dehydration, Resin-Embedding

Electron microscopy samples are often chemically fixed before dehydration, resin-embedding, and sectioning. But they can also be "fixed" by rapid freezing, in a way that precludes ice-crystal formation, to ensure minimal damage to the original cell structures. How can this be done?

A) High-pressure cooling
B) Plunging into liquid nitrogen
C) Spraying with a jet of liquid propane
D) Contact with a copper block cooled by liquid helium
E) All of the above