You are presented with the question "Which of the following keeps food viable for extended flights? " and the following answer choices: 
- evaporation
 - microwaving
 - boiling
 - freeze drying
 - layers of fat
 - deep frying
 - mechanical
 - Dehydration

Now knowing that astronauts require preserved food for extended flights and freeze-drying Freeze drying is a method of preserving materials, choose the best answer.


 

    freeze drying     