Lichens are not single organisms, but algae and fungi that function together. The algae use photosynthesis to make food for both organisms. The fungi produce digestive chemicals and absorb nutrients for both organisms. How does the biological activity of lichens cause weathering in rocks? Answer options with 4 options A. Lichens cause friction as they grow, which weathers the rocks. B. Lichens produce chemicals, which dissolve and weather the rocks. C. Lichens take in water, which freezes in cracks and weathers the rocks. D. Lichens absorb heat during photosynthesis, which weathers the rocks.