The World's 40,000 Known Species of Spiders ____

The world's 40,000 known species of spiders ____.

A) kill more livestock with poisonous bites than any other threat
B) have to be controlled in order for integrated pest management to work properly
C) are a threat not only to livestock, but also to rural farmers because they nest in sheds where equipment is stored and later retrieved
D) kill far more crop-eating insects every year than humans do by using chemicals
E) provide important food for birds that control caterpillar populations