In the Ant-Acacia Studies by Thomas Belt and Daniel Janzen

In the ant-acacia studies by Thomas Belt and Daniel Janzen, how does the relationship between ants and acacias affect the population of acacia trees?

A) It increases the population because ants defend the tree against predation.
B) It increases the population because ants leave organic matter in their nests.
C) It decreases the population because ants feed on the acacia's leaves and nectar.
D) It decreases the population because ants increase competition with other plants.
E) It has no effect on the population; ants simply use the acacia for food and nesting sites.