Many People Think Leaf-Cutter Ant Colonies Provide a Large Benefit

Many people think leaf-cutter ant colonies provide a large benefit to rainforest ecosystems. Which of these statements does not provide evidence to support this assumption?

A) Nitrogen fixation in fungal gardens of leaf-cutter ant colonies is very high.
B) Refuse areas of ant colonies contain about 48 times the nutrients in leaf litter.
C) Leaf-cutter ants till the soil near their colonies, allowing plant roots to penetrate more easily.
D) Leaf-cutter ants reduce above-ground net primary productivity by harvesting leaves; their effect on root growth is unknown but is likely positive.