Fact 1: Dehydrating food is used for preserving food.

Fact 2: Food is then dehydrated in slow oven or dehydrator.

Given the two facts above, answer the question "What is used to preserve food?" with the following options: 
- salt
 - Energy
 - oven
 - fats
 - sugar
 - sodium
 - marine
 - bamboo


 

   oven      