Which of the following associations is an example of mutualism

The association that is an example of mutualism is hydra viridis and zoochlorellae. In mutualism, both organisms benefit from the relationship. Hydra viridis, a freshwater invertebrate, harbors zoochlorellae, which are single-celled green algae that live inside its cells. The algae produce food through photosynthesis, which benefits both the algae and the hydra. The hydra, in turn, provides a protected environment and nutrients to the algae. Therefore, both organisms benefit from the association, making it an example of mutualism. The other options are not examples of mutualism; they are parasitic or commensal relationships.