Answer:
Symbiosis
Explanation:
Symbiosis is a physical association between two different organisms whereby both benefit from the relationship. A good example is the lichens. These are composite plants consisting of blue-green algae within the mycelial mass of fungus. The algae are provided with a means of attachment. They also obtain water, carbon dioxide and mineral salts from the fungus. The fungus obtains oxygen and carbohydrates made by algae through photosynthesis.
