Fact 1: Plants use cellulose for their cell walls.

Fact 2: Leaf blades contain cellulose and hemi-cellulose that are readily broken down by microbes.

Given the two facts above, answer the question "plants cell walls are readily broken down by what" with the following options: 
- Heavy rains
 - heat energy
 - acetic acid
 - microbes
 - fossil fuels
 - heat
 - bacteria
 - chemicals


 

    microbes     