The correct option is B Four
The class Osteichthyes includes bony fishes. They have a two-chambered heart, air bladder to regulate buoyancy and are oviparous as they lay eggs. The fertilisation is external and occurs in water.
Placoid scales are found in cartilaginous fishes such as sharks. Bony fishes have cycloid or ctenoid scales. Cycloid scales are large, thin and round or oval in shape and exhibit growth rings. Ctenoid scales resemble cycloid scales but have comb-like teeth on their overlapping edge.
Claspers are found in male sharks to hold females during mating.