The correct answer is C. Lichen.
Lichen is a composite organism that grows on rocks, trees, and other surfaces. It is made up of a fungus and an alga or cyanobacterium that live together in a symbiotic relationship. The fungus provides the alga or cyanobacterium with a place to live and protection from the environment, while the alga or cyanobacterium provides the fungus with food.
Litmus paper is made from lichens. It is used to test for acids and bases. When litmus paper is placed in an acidic solution, it turns red. When it is placed in a basic solution, it turns blue.
Ferns are a type of plant that reproduces by spores. They have feathery leaves and grow in moist, shady areas.
Algae are a type of plant that lives in water. They are usually green or brown and can be found in both fresh and salt water.
Fungi are a type of organism that does not have chlorophyll. They can be found in many different environments, including soil, water, and on plants.