Answer:
The correct answer is d. lichen
Step-by-step explanation:
Lichens is a symbiotic relationship between algae and fungi. In this relationship both the individual are benefited from each other. They are mostly found in moist areas.
Lichens provide nutrients to the algae from air and algae provide food in the form of carbohydrates to the fungi. Lichens are very sensitive to pollution because they easily absorb it. So they are used to check the environment quality of the area by scientists.
Lichens provide algae a wide range of habitat to grow without which algae cannot survive alone in these harsh condition, therefore, lichens are present all over the world.