Match the Column I with Column II :

A-2,B-1,C-3,D-4

A. Epiphytes - 2. Orchid on mango tree

B. Grazing cattle - 1. Cattle egret

C. Sea anemone - 3. Clown fish

D. Lice - 4. Ectoparasite

A. Epiphytes - 2. Orchid on mango tree: Epiphytes are plants that grow on other plants without harming them. Orchids are a common example of epiphytes, and they often grow on trees like mango trees.

B. Grazing cattle - 1. Cattle egret: Grazing cattle refers to cattle that feed on vegetation in a pasture or grassland. Cattle egrets are commonly seen around grazing cattle, as they feed on insects and parasites that are disturbed by the cattle's movements.

C. Sea anemone - 3. Clown fish: It is the interaction between sea anemone that has stinging tentacles and the clown fish that lives among them. The fish gets protection from predators which stay away from the stinging tentacles. The anemone does not appear to derive any benefit by hosting the clown fish.

D. Lice - 4. Ectoparasites: Lice are external parasites that live on the bodies of mammals or birds. They rely on their hosts for food and survival. As an ectoparasite, lice are found on the external surface of the host's body rather than living inside it.

These pairings explain the associations between the organisms in Column I (the given entities) and Column II (their respective characteristics or relationships).