If something made of glass , fiberglass , polyethylene, or vinyl  is used to protect plants from the cold, then what protects plants from the cold?

Answer choices:
- Something made of fruit or vegetables
 - series of enzyme-mediated reactions
 - Something made of glass, fiberglass, polyethylene, or vinyl
 - Something whose growth is discouraged by heavy wet soils
 - keeping food fresh for long periods of time
 - Something made of brick
 - Something made of metal
 - gas layer that surrounds earth

 

   Something made of glass, fiberglass, polyethylene, or vinyl       