Hint: Saprotrophs derive nutrients from the dead tissues or cells. They generally feed on dead and decaying matters by absorbing nutrients from them. They mostly depend on nonliving matters or matters which were alive for a certain period of time but are dead at the present.
Complete answer: Option A- Fungi- belong to the class saprophyte because they depend on dead and decaying matter for food. They obtain the dead tissues and help in reusing the nutrients in the ecosystem. Ganoderma, Pilobolus, Trametes are some examples of fungal saprophytes. They grow in the woods, swampy areas, logs, moist areas. Fungi are treated as food delicacies which include mushrooms. Some fungi are also responsible for causing fungal infections in humans.
Option B- Algae- these may be photosynthetic or autotrophs or parasitic, that is, they either make their own food with the help of sunlight or may depend on other organisms for food.
Option C- Lichens- maintain the symbiotic association between algae or a bacterium and fungi. Fungi get nutrients and food from the bacterium while the bacterium or algae achieves protection from the environment by the fungal filaments.
Option D- Bryophytes- these are the amphibians of the plant kingdom. They grow on land or soil but depend on water for sexual reproduction. This function doesn’t come under Class saprotrophs because they do not depend on the dead and decaying matter to obtain food.
So, option A is the correct answer.
Note: Saprotroph is also known as detritivores, saprophytes. They are not parasites as they do not depend on living organisms, rather they depend on dead and decaying organic matter mostly.