Agreenhouse is used to protect plants from the cold, and the air in the greenhouse is humid. Given these facts, what are two things that are important for plants among the following options:
- organic material
 - Bubbles and soap
 - Humidity and protection
 - excretory structures
 - Sand and rocks
 - Darkness and cool winds
 - food and shelter
 - genetic diversity


 

   Humidity and protection      