A lichen is an organism that structurally appears to be a single organism. But a lichen is actually two different organisms—a fungus and green algae—living together as one organism. The fungal partner derives its nutrition from the photosynthesizing algae. How does a lichen differ in its photosynthetic activity from Elysia chlorotica, the sea slug that’s considered to be a photosynthesizing animal? A. In lichens, the fungi photosynthesize on their own, while Elysia chlorotica forms a relationship with a photosynthesizing plant. B. In lichens, the relationship with the algae lasts throughout the life cycle, but in Elysia chlorotica, the relationship occurs only during the immature juvenile stage of the slug’s life cycle. C. Lichens can photosynthesize only because of the living algal partner, while Elysia chlorotica incorporates chloroplasts from algae into its cells. D. In lichens, the association between the fungi and algae is permanent, while Elysia chlorotica associates with a photosynthesizing organism only when it requires food.