Which of the following is an example of commensalism?

All of the above

The correct answer is (d) All of the above.

a-Orchid growing as an epiphyte on a mango branch

b-Barnacles growing on the back of a whale 

c-Cattle egret foraging near grazing cattle 

Explanation: In commensalism, one species benefits while the other is neither harmed nor benefited.

• The example of an orchid growing as an epiphyte on a mango branch represents commensalism because the orchid benefits by using the tree as support and accessing sunlight, while the mango tree is not affected.
• Barnacles growing on the back of a whale is another example of commensalism. The barnacles benefit by having a stable substrate to attach to and access to food particles in the water, while the whale is not significantly affected.
• The association between cattle egrets and grazing cattle is also an example of commensalism. The egrets benefit by foraging near the cattle and feeding on insects stirred up by their movement, while the cattle are not impacted by the presence of the egrets.

In all these cases, one species benefits while the other is not harmed nor benefited, illustrating the concept of commensalism.