The correct answer is The Fungus makes available the moisture and minerals to Algae, which prepare food by photosynthesis. Explanation & Key Takeaways: • Lichens are formed by the symbiotic association between algae and fungi, and have a unique morphology distinct from both the parents. • Lichens are very sensitive to sulphur dioxide pollution in the air. • If air is very badly polluted with sulphur dioxide there may be no lichens present in that area. • The growth rate of lichen is very low even less than a millimeter per year and this property is used to determine the age of the exposed rock. • The fungi benefit from the carbohydrates produced by the algae or cyanobacteria via photosynthesis. • The photobiont (A photosynthetic symbiont, especially in symbiosis with fungi in lichen) supplies the association organic carbon from photosynthesis, and the mycobiont (The fungus that is a component of a lichen) ensures protection and regulates the supply of minerals and water. • The nutritional exchange between partners is probably much more complex than the exchange of water and minerals for organic carbon.