Fact 1: Earthworm burrows help aerate soil, which is also good for plants.

Fact 2: Earthworms help soils breathe.

Given the two facts above, answer the question "What helps soil breathe?" with the following options: 
- the circulatory system
 - gasoline
 - loose dirt
 - temperature
 - evaporation
 - Exfoliation
 - aeration
 - bacteria


 

       aeration  