Examples that show commensalism are :

(i) An orchid growing on mango tree

(ii) Cuckoo bird and crow

(iii) Cuscuta growing on Nerium tree (iv) Barnacles growing on a whale

The correct option is (i) and (iv).

Commensalism is a type of symbiotic relationship between two organisms of different species in which one organism benefits from the association, while the other is neither helped nor harmed (remains unaffected).
Let us analyze each of the given examples to determine the type of interaction:

(i) An orchid growing on a mango tree:
An orchid is an epiphyte (a plant that grows on another plant for physical support but does not derive nutrition from it). The orchid benefits by getting better access to sunlight and air, while the mango tree is neither harmed nor benefited. Therefore, this is an example of commensalism.

(ii) Cuckoo bird and crow:
The cuckoo bird lays its eggs in the nest of a crow, forcing the crow to hatch and rear the cuckoo's young. This is a classic case of brood parasitism. The cuckoo benefits, while the crow is harmed (loses resources and its own offspring may be neglected or killed). Therefore, this is an example of parasitism.

(iii) Cuscuta growing on Nerium tree:
Cuscuta (commonly known as dodder) is a parasitic plant that lacks chlorophyll and leaves. It penetrates the host plant (the Nerium tree) using specialized roots called haustoria to draw water, minerals, and nutrients. The Cuscuta benefits while the Nerium tree is harmed. Therefore, this is an example of parasitism.

(iv) Barnacles growing on a whale:
Barnacles attach themselves to the skin of whales. This helps the barnacles as they are carried to plankton-rich waters for feeding, and they also get protection from predators. The whale is unaffected by the presence of the barnacles. Therefore, this is an example of commensalism.

Since statements (i) and (iv) represent commensalism, the correct option is (i) and (iv).