Final answer:
Osteichthyes, or bony fish, are able to breathe without swimming primarily because they can move their operculum, which allows water to flow over their gills. The swim bladder is used for buoyancy control, not directly for breathing.
Step-by-step explanation:
Osteichthyes, commonly referred to as bony fish, have several adaptations that enable them to breathe without swimming. The correct answer to the question of why Osteichthyes are able to breathe without swimming is: A. They can move their operculum, which covers the chamber near their gills. The operculum is a protective, muscular flap that allows water to be drawn over the gills, thereby permitting the fish to extract oxygen from the water. Bony fishes do possess a swim bladder. However, the primary function of the swim bladder is to control buoyancy, not for storing air to assist with breathing. While it is true that not all fish need to be in motion to breathe, and many bony fish have developed this operculum mechanism that aids in water flow over their gills, the swim bladder's role is connected to buoyancy rather than respiration.
Therefore, the statements B. "They have a swim bladder that stores air for them" and C. "All fish can breathe without swimming" are not accurate in the context of how fish breathe.