Answer: The correct answer is- This relationship is one of example of mutualism.
Mutualism can be described as a biological interaction between two species that live in close association with each other in a way that both the partners are benefited from each other. It is a type of symbiotic relationship.
Lichen shows mutualistic relationship between algae and fungus, where photosynthetic algae provides food source to the fungi and fungi in return provides protection to algae as well as provides nutrients from the surrounding.
Thus, it is an example of mutualism.