Fact 1: Agreenhouse is used to protect plants from the cold.

Fact 2: Molecules expand with heat and contract with cold.

Given the two facts above, answer the question "What is used to protect plants from contracting molecules?" with the following options: 
- greenhouses
 - staying warm
 - Enzymes
 - earmuffs
 - electricity
 - jackets
 - sweaters
 - exoskeleton


 

 greenhouses        