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

Fact 2: Flowers are beautiful kinds of plants.

Given the two facts above, answer the question "A greenhouse is used to protect flowers from what?" with the following options: 
- sunlight
 - fertilizer
 - salinity
 - Dehydration
 - cold air
 - the cold
 - Winter
 - irrigation


 

      the cold   