Fact 1: Annelids are worms such as the familiar earthworm.

Fact 2: Earthworms are invaluble for soil health.

Given the two facts above, answer the question "What are invaluable for soil health?" with the following options: 
- bacteria
 - annelids
 - sharks
 - Exfoliation
 - bioaerosols
 - plankton
 - evaporation
 - sunlight


 

  annelids       