Let's check the presence of cell walls in the given organisms: A) Bacteria have cell walls typically made of peptidoglycan. B) Diatoms are a type of algae belonging to Protista; they have unique cell walls made of silica, called frustules. C) Mushrooms are fungi; fungal cells have cell walls made primarily of chitin. D) Tapeworms are multicellular animals (Platyhelminthes). Animal cells characteristically lack cell walls.