Which choice is an example of a symbiotic association of a protozoan with its mode of association?

An example of a symbiotic association involving a protozoan is the relationship between termites and the protozoan Trichonympha. In this association, Trichonympha lives in the guts of termites and helps them digest cellulose from wood, which the termites cannot break down on their own. In return, the protozoan receives a nutrient-rich environment and access to food. This mutualistic relationship benefits both organisms, showcasing a symbiotic association.