Which example illustrates commensalism?
Cattle have an organism called a protozoa living in their gut. The protozoa digest cellulose. The cows are able to feed on grass, while the protozoa are sheltered inside the cow.
Hippo dung (feces) is eaten by a large species of catfish native to African lakes. The catfish typically follow the hippo herds so they can get food.
Oxpecker birds remove parasitic fly larvae from the skin of buffalo. In exchange, they are protected from predatory cats, who will not challenge a buffalo to try to eat the Oxpecker bird.
Ants help to take care of aphid insects like humans take care of cattle. Aphids suck the sap out of trees, which ants also feed on. In turn, the ants sting predators that attack the aphids.