The correct option is A symbiosis
Termites have a symbiotic mutualistic relationship with protozoa that live in the insect’s gut. The termite benefits from the ability of bacterial symbionts within the protozoa to digest cellulose. The termite itself cannot do this, and without the protozoa, it would not be able to obtain energy from its food (cellulose from the wood it chews and eats). The protozoa and the bacterial symbionts benefit by having a protective environment and a constant supply of food from the wood chewing actions of the termite.
A commensal relationship occurs when one species benefits from the close, prolonged interaction, while the other neither benefits nor is harmed.