Agreenhouse is used to protect plants by keeping them warm, and angiosperms are the flowering plants. Given these facts, a greenhouse is used to protect angiosperms how among the following options:
- their hosts
 - by keeping them underground
 - by keeping them warm
 - by keeping them outside
 - by keeping them exposed
 - Exfoliation
 - organisms and their habitat
 - In the winter


 

   by keeping them warm      