Which of the following is an example of parasitism? Fleas are common reasons animals itch because they bite the animal's skin suck blood, and create a warm home for themselves. Corals in aquatic ecosystems provide shelter to zooxanthellae that produce sugar for the corals to feed on. Cattle egrets do not bother livestock while they eat the insects that are exposed due to livestock grazing. In the savanna, giraffes use their long necks to eat the leaves from a branch on a tall tree.

Parasitism is a type of symbiotic relationship where one organism, the parasite, benefits at the expense of the other, the host. In the given options, the relationship between fleas and animals is an example of parasitism. Fleas bite the animal's skin to suck blood, which benefits the flea but harms the animal, causing it to itch. The other options describe different types of symbiotic relationships but not parasitism. Corals and zooxanthellae have a mutualistic relationship, where both benefit. Cattle egrets and livestock have a commensal relationship, where the egret benefits without affecting the livestock. Giraffes eating leaves from a tree is not a symbiotic relationship; it's just a description of feeding behavior.