Fact 1: Decomposition increases amount of organic matter in soil.

Fact 2: Organic matter is the plant and animal residue in the soil at various stages of decomposition.

Given the two facts above, answer the question "What decomposes in soil?" with the following options: 
- swamp vegetation
 - roundworms
 - Echinoids
 - tunicates
 - Earthworms
 - some invertebrates
 - most cephalopods
 - Plant and animals


 

        Plant and animals 