Fact 1: Hydrogen bonds cause water to expand when it freezes.

Fact 2: Frostbite is the actual freezing of tissue.

Given the two facts above, answer the question "What causes frostbite of tissue?" with the following options: 
- an object
 - hydrogen bonds
 - heating liquids
 - Veins and arteries.
 - Generating heat
 - evaporation
 - heat produced
 - dehydration


 

  hydrogen bonds       