Fact 1: Decomposition increases the amount of nutrients in the soil.

Fact 2: Moisture is needed for bacterial decomposition.

Given the two facts above, answer the question "what are able to increase the amount of nutrients in the soil" with the following options: 
- Frogs
 - farms
 - mussels
 - bacteria
 - clams
 - plants
 - acid rains
 - tractors


 

    bacteria     