Question: Leaves fall from deciduous trees onto the forest floor. These leaves decay slowly and become part of the topsoil. Which change is most likely to have a positive impact on the nutrients available in the topsoil?

  Options: 
 A. a decrease in temperature
 B. a decrease in biodiversity
 C. an increase in the number of predators
 D. an increase in the number of decomposers 
Answer: D