Sharks and dogfishes differ from skates and rays because (a) gill slits are ventrally placed (b) head and trunk are widened considerably (c) distinct demarcation between body and tail (d) their pectoral fins distinctly marked off from cylindrical bodies.
Option D Sharks and dogfishes have cylindrical body while skates and rays have both of their pectoral fins fused. It gives a winglike appearance and are not distinct from body.
