Answer the following question given this paragraph: 

When sunlight heats Earth’s surface, some of the heat radiates back into the atmosphere. Some of this heat is absorbed by gases in the atmosphere. This is the greenhouse effect , and it helps to keep Earth warm. The greenhouse effect allows Earth to have temperatures that can support life.


Q: What effect in the atmosphere ensures that the earth maintains the correct temperature to support life?

 Choices:

- coriolis effect

- ozone effect

- smog effect

- greenhouse effect

A:
greenhouse effect
