Question

All mammals have hairs except
(a)Cetaceans
(b)Chiropterans
(c)Primates
(d)Rodentians

Answer 1

One of the major organisms present in this order are the blue whales. Blue whales are mammals but are aquatic and don’t have hair. The presence of blubber helps them to protect from cold instead of hair.

Complete answer:
Cetacea is a broadly divided and unique order, which is full of aquatic marine organisms. Cetaceans include whales and dolphins which are the biggest group of mammals without hair. The presence of blubber for insulation is the reason why the hair on their body.

Additional Information: -Mammals (means "breast" in Latin) consists of vertebrates and are differentiated by the presence of mammary glands by which the females feed their children by producing milk.
-The neocortex which is a part of the brain, fur, hair, and the ear bones are the characteristics that differentiate mammals from reptiles and birds.
-The common ancestor for mammals, reptiles, and birds are Carboniferous, which went through divergent evolution 300 million years ago. Depending on the environment each organism adapted and humans became apex due to the neural development.
So the correct answer is ‘cetaceans’.

Note: -Most mammals have higher intellectual and brain activity and some have large brains, awareness, and use tools for hunting. They are also known for communicating and having vocalized in different ways, such as the creation of ultrasound, marking using smell indicators, alert signals, singing, and even echolocation.
-Many mammals are domesticated by humans, wherein evolution man found tools for hunting and farming which made them dominant in the ecosystem.
-Mammals include herbivores, carnivores, and omnivores and the constant need to maintain body temperature makes them feed in regular time.