What are the structural adaptation of whales and dolphins (compare them please)

Whales and dolphins are mammals and have lungs instead of gills for breathing. They have blowholes at the tops of their heads that function like nostrils; they need to put their heads above water every so often to breathe. Both dolphins and whales have hair instead of scales, another quality that is specific to mammals. The animals have live births instead of laying eggs, and baby dolphins and whales nurse from their mothers. Whale and dolphin births take place near the surface of the water, so the young animals can easily take their first breath.

Both whales and dolphins rely on the sounds they make for survival, even though the sounds are utilized differently by each animal. For instance, whales make high-pitched groans and whistles to communicate with one another to warn against danger or navigate during migration

COMPARISON AND CONTRAST OF WHALES AND DOLPHINS

Both dolphins and whales belong to the cetacean family and are marine animals that reside in the ocean. Some scientists even assert that dolphins are a type of whale, as the two animals have a number of shared characteristics. However, there are distinct differences between whales and dolphins as well that will teach you more about the physical appearance of these marine creatures and how they survive in their environment.

b would be the right answer