Which interaction best exemplifies a parasitic relationship?

A parasitic relationship is characterized by one organism benefiting at the expense of another, often causing harm to the host organism. In this scenario, when wasps lay their eggs inside caterpillars, they are utilizing the caterpillar as a host for their larvae. The developing wasp larvae benefit by feeding on the caterpillar tissues, ultimately leading to the death of the caterpillar. This interaction illustrates the essence of parasitism, where the wasp gains nutrition and a safe environment for its own offspring while the caterpillar suffers significant harm and ultimately does not survive the process.

The other options depict different types of ecological interactions that do not fit the definition of parasitism. Cleaning birds benefiting from removing parasites from mammals illustrates a mutualistic relationship, where both species gain advantages. Pollination by bees showcases mutualism as well, with the bee receiving nectar and the flower benefiting from reproduction. Lastly, fish using anemones for shelter exemplifies commensalism, where one organism benefits while the other is neither helped nor harmed.