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).

Step-by-step Explanation:

Commensalism is a type of biological interaction in which one organism benefits while the other organism is neither helped nor harmed (+ / 0 relationship). Let us analyze each of the given examples to identify which ones show commensalism:

(i) An orchid growing on a mango tree:
The orchid grows as an epiphyte on the branches of the mango tree to get better access to sunlight and air. The orchid benefits from this physical support (indicated by a '+' sign), while the mango tree is neither harmed nor benefits in any significant way (indicated by a '0' sign). Therefore, this is an example of commensalism.

(ii) Cuckoo bird and crow:
The cuckoo bird lays its eggs in the nest of a crow. The crow hatches the cuckoo's eggs and rears the chicks, often at the expense of its own offspring. This is a classic case of brood parasitism (+ / - relationship), which is a form of parasitism, not commensalism.

(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 (like the Nerium tree) using specialized structures called haustoria to absorb nutrients and water. Here, Cuscuta benefits (+) and the host tree is harmed (-). Thus, this represents parasitism, not commensalism.

(iv) Barnacles growing on a whale:
Barnacles attach themselves to the skin of whales. This helps the barnacles to be carried to different areas rich in plankton for feeding, and protects them from predators. The barnacles benefit (+), while the whale is unaffected (0) by their presence. Therefore, this is an example of commensalism.

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