Freeze drying works in two clear stages. First, the food is cooled well below its eutectic temperature so that every bit of water, including the water bound with dissolved solids, turns into solid ice. Second, the frozen food is placed in a chamber where the pressure is dropped far below atmospheric pressure and a small amount of heat is supplied. At this low pressure, ice cannot exist as a liquid in between, so it converts straight from solid to vapour. This is exactly what sublimation means, and it is why the process is also called lyophilization.
Now check the distractors again. IQF just means freezing units of food individually and fast so ice crystals stay small, there is no vapour step involved. Ordinary freezing stops at making ice, it does not remove that ice afterward. Freeze encapsulation is not a recognized preservation method in food engineering. Since only freeze drying matches solid ice to vapour after freezing below eutectic point, the answer is confirmed.
\[\boxed{\text{Freeze drying}}\]