How are  natural  forest fires beneficial to forest...

How are natural forest fires beneficial to forest ecosystems? Select all that apply.

a. they allow for a "blank canvas" so that humans can come in and plant non-native species

b. they help to maximize plant biodiversity by keeping species in check that would prohibit others from growing

c. smaller fires prevent buildup of dead trees and branches that could lead to a larger, more catastrophic fire

d. they prevent overpopulation of certain animal pests