Tropical leafcutter ants collect leaf cuttings, which they transport to special underground chambers. There, they chew the leaves to create nursery beds on which they grow a species of fungus they use for food. When ant queens disperse to establish new colonies, they carry the fungus with them, dispersing it as well (this benefits the fungus). In the ants’ nest, the fungus is at risk of being replaced by another fungal species that is able to grow in the same habitat, using the same limited resources. On their bodies, the ants carry and provide a home for bacteria that produce antibiotics the ants use to kill this second fungus and thereby protect their food supply. In this system, the relationship between the two fungal species is:

a. parasitism.
b. predation.
c. mutualism.
d. commensalism.
e. interspecific competition.